Hundreds of police officers scoured a Saint Petersburg, Florida, neighborhood Tuesday for a police officer's killer, vowing to hold a perimeter around the crime scene until they've searched every nook where a person could possibly hide.

The killing was the third death of a law enforcement officer in the city in less than a month.

The search, involving hundreds of officers, scent dogs and aircraft, forced the closure of several nearby streets and three schools. School officials sent students to other locations for the day.

Police Chief Chuck Harmon said a pair of flip-flops found in two places near the shooting site could be clues in the investigation, and said they have a video that could also help in identifying the suspect. So far the suspect has not been seen since Officer David S. Crawford confronted him late Monday night.

A gunfight erupted moments after Crawford stepped out of his cruiser. When it was over Crawford, 46, had been fatally shot multiple times at close range.

Crawford was not wearing a bulletproof vest at the time, Harmon said. Department policy doesn't require officers to wear vests. While declining to describe Crawford's fatal wounds, he said a vest would not have necessarily saved his life.

The FBI offered a $50,000 reward leading to the arrest and conviction in Crawford's death.

Crawford had been summoned to the scene to investigate a suspicious person who was reportedly toting a brick in a resident's backyard, according to police.

"It hurts. It stings. This killer has taken somebody very precious to us, a member of our family," Harmon said Monday night.

"We have a killer on the loose that we're going to use every resource that we have to try and locate and apprehend," he said.

Harmon described Crawford as a family man who loved horses and had a knack for talking with people. He spend most of his time working the midnight shift and loved it, Harmon said.

"He was an honorable man," Harmon said of Crawford, who had a wife and a 24-year-old daughter.

His shooting marked the third death of a law enforcement officer in Saint Petersburg this year.

Two Saint Petersburg officers died and a U.S. marshal was wounded January 24 in a gunfight with a suspect who was hiding in an attic.

Those officers had gone to a home to inquire about a man who was wanted by police. A relative told them he was upstairs and might be armed. As they approached, police say the man -- Hydra Lacy Junior -- fired on the officers, striking one. Another officer died in the ensuing gunfight.

Police eventually used a backhoe to tear a hole in the house. They found Lacy, dead.

The spate of shootings has shaken the city and its police department, Mayor Bill Foster said.

"Well, I'm not going to lie, this city has been through hell," he said.