Authorities were trying to determine the cause of a loud sound that emanated from a trash can outside the Clarence M. Mitchell Jr. Courthouse in downtown Baltimore on Thursday afternoon, leading authorities to evacuate the building and shut down city streets.
Officials said nobody was hurt and nothing was damaged in the incident, which occurred about 2:30 p.m. They were unable to identify the source of the noise or find any incendiary device.
"It can't really be pinpointed at this time" said Lt. Carla Lightsey, a spokeswoman for the Baltimore City Sheriff's Office, told reporters at the scene.
When asked if authorities believed someone had intentionally detonated an explosive device, she said, "All sources would probably point that there was something put there."
Police blocked off streets around the courthouse in the 100 block of N. Calvert St. as police, sheriff's deputies and emergency workers investigated what was initially reported as an explosion.
Lightsey said it was a "very loud sound" but did not use the word "explosion." There had been no threats against the courthouse, which was evacuated after the sound.
Eugene Barnes, who was serving on a jury in the courthouse, said he could hear a "boom" from inside the courtroom. He described it as akin to a muffled "large-caliber gun." Proceedings continued in the case he was hearing, though court was soon dismissed.
"We didn't think anything of it" until police showed up with lights and sirens, he said.
Jurors watched as hazardous-material teams and other police personnel arrived. Shortly thereafter, Barnes said, the building was evacuated.
He said he realized then that it was serious.
"OK, it's a little deeper," he said.
People milling outside other buildings near the courthouse said they didn't hear anything and were surprised to find police at the scene.
About 4 p.m., police sent a robot across Fayette Street toward the courthouse to knock over a trash can in front of the building.
The robot picked at some of the garbage that spilled out, then was withdrawn as human investigators examined the contents.
Agents from the Department of Homeland Security and the Bureau of Alcohol, Tobacco, Firearms and Explosives also responded. The Baltimore sheriff's office took the lead in the investigation; Baltimore police assisted.
"Right now we have very little information," said Lt. Col. Melissa Hyatt, the Baltimore Police Central District commander.
In earlier versions of this article, comments made by Lt. Carla Lightsey, a spokeswoman for the Baltimore City Sheriff's Office were misattributed to Lt. Col. Melissa Hyatt of the Baltimore police.
Baltimore Sun reporter Carrie Wells contributed to this article.