The radio in the emergency medical vehicle crackled - the stifling heat had overwhelmed someone on Lexington Street.
Capt. Charles Cheelsman turned on the vehicle's lights and sirens and hit the accelerator. Cars swerved to get out of the way as he sped toward Lexington Market.
When he got there, he found Murdis Ferguson, 52, drooping in a plastic chair. She had been walking with a friend, Celeste Gross, also 52, when she was overcome by the heat.
Yesterday, the temperature hit 98 in the city, but it felt like 106, according to the National Weather Service.
When it gets that hot and the emergency calls start rolling in, Cheelsman helps coordinate emergency calls and makes a special effort to keep emergency rooms from becoming clogged with victims. Sometimes he goes out on the streets to see that the system is running smoothly.
The policy went into effect almost a year ago after too many patients were transported to overloaded hospitals, said Cheelsman, who supervises the city's Northeastern Emergency Medical Services District. The back-ups tied up emergency medical personnel at the hospitals.
"The main objective is to make sure our people get back out there faster," Cheelsman said of the policy.
Cheelsman was responding to heat-related calls yesterday, no matter what part of the city they came from. One heat victim turned up unexpectedly. As the team loaded Ferguson onto a stretcher, a man walked into the scene, tugging his wife by the arm.
"Excuse me, can she sit down?" said Dwayne Kittrell, 43, gesturing to a tiled ledge in front of an area that's used for entertainment. "She's getting ready to fall down."
Diane Bollock, 35, slumped on the ledge as the medical team took her blood pressure.
"Everything just sort of flashed before my eyes," she said in a slow murmur. "I felt dizzy. I can't breathe."
The couple had walked for about 15 minutes from a bus stop to get to the market, Kittrell said, and they had been in the air-conditioned shopping center for five minutes when Bollock started feeling ill.
Kittrell said his wife had some water earlier, but she corrected him and said it was actually a soft drink.
That didn't help, Cheelsman said, because sodas dehydrate people. A recent operation may have worsened her condition, he said.
On a normal day, Cheelsman makes sure operations in his district are running smoothly. Often he does his job in front of a computer directing emergency medical units, especially when it's busy.
Yesterday, city emergency medical teams were overloaded by noon, but another supervisor managed the computer so Cheelsman could help answer calls.
Emergency responders answered eight heat-related calls when Baltimore's heat wave began Sunday and responded to five Monday, city records show.
Not long after Cheelsman left Lexington Market, there was a call in the 1000 block of Saratoga St. He found a gray-haired man in jeans, a heavy shirt and socks sitting on the steps of an abandoned rowhouse.
Sweat poured from his bowed head and a strand of saliva dangled from his mouth as he weakly sipped a bottle of water a bystander had given him. His speech was incoherent.
"I noticed him sitting in the road right there," said Gary Antoine, 34, who was on an errand for the summer camp he coordinates nearby.
"No one was attending to him, so I moved him over to the side," Antoine said.
Then he called 911, he said.
A medical crew transported the man to a hospital. After Cheelsman got into his van, he received another call and sped to the 1300 block of N. Stricker St. where he found a man lying under a tree.
He wore a wool hat, wool socks and sweat pants. As he lay on his back, he said: "Who's that man?" and pointed skyward at the top of the tree where there was no one.
The patient was delirious from the heat and from alcohol, said paramedic Stephanie Cisneros.
"We can't even understand what he's saying," she said.
After the call on North Stricker, Cheelsman headed to Light Street in South Baltimore to respond to a homeless man who thought he had a seizure.
"I felt just nervous, shaky," the man said, trembling in the back of an ambulance. He had been outside all day and had not had anything to drink anything, he said.
That made the fifth heat-related call Cheelsman answered before yesterday's thunderstorm struck at around 2 p.m. First rain, then pellets of hail bounced off of Cheelsman's windshield as he swiftly turned off the blasting air conditioner.
"That will be a big relief," he said. "It will get a lot of people out of the streets, and the people who don't want to get off the street, it will cool them off."
The state medical examiner's office had not linked any city deaths to heat-related causes as of Monday, said Nicole Leistikow, an assistant to Baltimore's health commissioner, Dr. Joshua M. Sharfstein.
The city health department will check again today, she said.
Although the temperature dropped after the storm, Cheelsman said he expected more heat calls.
"You get the heat-related stuff after the sun goes down because people get dehydrated," he said as he drove through a low-income neigborhood where many residents lack air conditioning. "They're told to stay outside, stay out of the heat, and sometimes, unfortunately, staying inside is worse."