Officials declined to name the two deputies who were killed. Sheriff Jeffrey R. Gahler said one had served on the force for 30 years and was assigned to the courts services division, and the other had served for 16 years and was assigned to the community services division.
"Today is a sad day for the Harford County sheriff's office and the citizens of Harford County, who we are sworn to serve," Gahler told reporters Wednesday afternoon, and bowed his head. "It is with great sadness that I tell you both deputies who were shot earlier today have succumbed to their injuries."
The suspect was identified as David Brian Evans. Gahler said there were two warrants for Evans' arrest — a criminal warrant for allegedly assaulting a police officer in Florida and a civil warrant issued in Harford County.
Gahler said he believed Evans targeted one of the deputies inside the Panera "because he was in a police uniform."
The deputies are believed to be the first in Harford to be killed by gunfire on duty in more than a century.
The incident Wednesday was the first time in almost 15 years that two Maryland law enforcement officers were killed in a single shooting.
Two Prince George's County sheriff's deputies were shot and killed in a 2002 incident. Two officers were shot to death in 2001 in a trailer park in Centreville on the Eastern Shore.
In Abingdon on Wednesday, deputies scoured multiple crime scenes for evidence hours after the shooting.
The incident took about 15 minutes, officials said. It began when a deputy was shot in the head inside the restaurant in the 3400 block of Merchant Blvd. about 11:45 a.m., officials said.
Gahler said the deputy was responding to a call from the restaurant. He said he was unsure of the nature of the call.
After shooting the deputy, the gunman fled the restaurant, officials said. Witnesses pointed other deputies toward the Park View apartments, a senior living complex next to the shopping center on Box Hill South Parkway.
Gahler said two other officers fired weapons at the scene. Both have been placed on administrative leave.
He said the investigation remains in the preliminary stages.
"We fully suspect that both deputies were shot by the same suspect," Gahler said. "We are not looking at anyone else. We believe it's an individual who's no longer a threat to the community."
No customers inside the Panera were injured.
Evans had an open criminal case in Florida for an alleged reckless-driving incident, according to online court records. The incident was alleged to have occurred last April. Evans then didn't show up for a court date.
Lynn Faulkner and her daughter Sophia were having lunch on a snow day at Panera Bread restaurant in Abingdon just before noon Wednesday when Sophia heard what she thought was glass breaking. Then the 15-year-old turned and saw a sheriff's deputy shot in the head. She said she froze as she tried to process what was happening.
Harford County Executive Barry Glassman said Evans was an "outsider," not a member of the community.
"What little we know of the suspect is that it looks like he was somewhat of a vagrant, someone who moved around a lot," Glassman said. "Whether you're serving a summons or warrant, a guy like that, who has a pistol on his body in a public place and is willing to go outside and shoot an officer, is a risk to all us."
Glassman said the two deputies showed "selfless dedication." He ordered Harford County flags to be lowered to half-staff.
"We are grateful that these deputies did give the ultimate sacrifice for all of us," he said. "We also want to celebrate, with their families, their lives and their dedication to service."
"The first lady and I send our most sincere thoughts and prayers to the families and loved ones of the brave deputies who made theultimate sacrifice today for the community they selflessly served," Hogan said in a statement. "It is my hope that their commitment and dedication to law enforcement and protecting otherswill be remembered and will forever serve as an inspiration to others."
He said state police were working closely with Harford County as needed.
A spokeswoman for Panera said the restaurant would remain closed during the investigation.
"Our thoughts and actions now are directed towards the victims and their families," the company said in a statement.
Former Harford County Sheriff L. Jesse Bane said he listened to the incident unfold on police radio.
The deaths will strike the department hard, he said, because law enforcement officers form tight bonds.
"You become part of a family," said Bane, the current town administrator in Bel Air. "That's what makes these things very difficult for law enforcement agencies to deal with."
"We've lost two brothers," he said.
Law enforcement in Harford County has suffered a series of losses in recent years.
The sheriff's office, composed of roughly 300 sworn officers, suffered the back-to-back deaths in September 2012 of Cpl. Charles Barton Licato and Sgt. Ian A. Loughran.
Licato, 34, was killed in an early-morning crash along U.S. 1 near the Conowingo Dam. His car left the road, slid down an embankment, and hit a pole and two trees before catching fire in a ravine.
An eyewitness describes what she saw at a shooting involving Harford County sheriffs in Abingdon Wednesday, Feb. 10.
Loughran, 43, had mentored Licato. He suffered a heart attack at Licato's funeral.
Also that month, the nearby Aberdeen Police Department endured the loss of Officer Charles N. Armetta, 29, who fell 47 feet to his death in an off-duty accident, and veteran Detective Mark A. Franklin, 55, who died of non-Hodgkin's lymphoma.
Baltimore Sun Media Group reporters David Anderson, Erika Butler, Colin Campbell, Tim Prudente, Kevin Rector, Sean Welsh and Bryna Zumer contributed to this article.
Editor's Note: An earlier version of this story incompletely referred to incidents in which two law enforcement officers were shot in a single incident. Two members of the Prince George's County sheriff's office were fatally shot in the line of duty in 2002.
Law enforcement deaths in Md. since 2010
Dec. 10, 2015: Noah Leotta, 24, Montgomery County, hit by drunken driver during traffic stop.
March 7, 2015: Brennan Rabain, 26, Prince George's County, accident while attempting traffic stop.
Jan. 9, 2015: Craig Chandler, 27, Baltimore, mortally wounded in crash during pursuit.
Dec. 21, 2014: Jamel Clagett, 30, Charles County, single-vehicle crash driving home from work.
Aug. 28, 2013: Jason Schneider, 36, Baltimore County, shot and killed trying to serve a warrant.
Oct. 18, 2012: Kevin Bowden, 28, Prince George's, crash while off-duty in cruiser.
Sept. 13, 2012: Ian Loughran, 43, Harford County, heart attack within 24 hours of shift.
Sept. 6, 2012: Charles Licato, 34, Harford County, crash while likely driving home from work.
Aug. 29, 2012: Forrest Taylor, 44, Baltimore, mortally wounded in crash driving to aid fellow officer.
Aug. 20, 2012: Adrian Morris, 23, Prince George's, crash during pursuit.
Jan. 27, 2012: William "Bill" Talbert, Montgomery County, hit by drunken driver.
May 21, 2011: Shaft Hunter, 39, Maryland State Police, crash while thought to be chasing speeding motorcyclist.
Jan. 9, 2011: William Torbit Jr., 34, Baltimore, shot by fellow police while working in plainclothes.
Nov. 29, 2010: Teresa Testerman, 54, Harford County, heart attack after responding to overcrowded cell block.
Oct. 20, 2010: Thomas Portz Jr., 32, Baltimore, cruiser hit the back of a fire engine.
Sept. 27, 2010: James Fowler III, 61, Baltimore, crash during inclement weather.
June 11, 2010: Wesley Brown, 24, Maryland State Police, shot while working as security guard.
April 4, 2010: Hector Ayala, 31, Montgomery County, car crash responding to back up fellow officer.
March 9, 2010: Thomas Jensen, 27, Prince George's County, crash responding to a burglary.