The firefighter, Leonard Riggins, died later at a hospital from a gunshot wound to the chest. Riggins, 52, was a 14-year veteran of the St. Louis Fire Department and left behind a wife and children.

"He stopped, he tried to help, and he was shot for no reason at all," said St. Louis Fire Chief Dennis Jenkerson, speaking at Christian Northeast Hospital on Wednesday night.

Authorities were still trying to reconstruct the chain of events Wednesday night but said it appeared the man who killed the firefighter carjacked or attempted to carjack four cars within a span of minutes. They did not release any information on the carjacker late Wednesday and didn't have a motive for his crimes.

Moszell and Nicara Kent were two of the man's victims. They pulled into their driveway on Perthshire Drive off Spring Garden Drive about 5 p.m. In the car were two of their children, ages 4 and 11.

Moszell Kent, 31, confronted a man who he thought was trying to jump their fence, and the man reached under his black, zip-up sweater and pulled a gun. The family was able to get out of the car before the gunman took it and drove up Perthshire toward Spring Garden.

Moszell Kent called 911 for help and chased after the car so he could tell police where the man went. When he reached the intersection of Spring Garden and Perthshire, he saw a wrecked car -- apparently previously crashed by the carjacker. That car, too, may have been taken from someone.

The carjacker crashed the Kents' car a few blocks away at Spring Garden and Dudley Drive. That's where Riggins, in his uniform and driving an

unmarked Fire Department vehicle, approached the wrecked car thinking he was coming to the aid of a motorist.

"He thought he came upon an accident scene," said St. Louis County Police Chief Jerry Lee. "He was trying to help."

Lee said the carjacker may have thought Riggins was a police officer. He struggled with Riggins, shot him and took his car, Lee said.

"He drove off, leaving the firefighter on the asphalt," Lee said.

St. Louis County police officers responding to a 911 call reporting an accident came upon the carjacker just a few minutes later. At Spring Garden and Riverview, the gunman was trying to switch the firefighter's car for yet another carjacked vehicle when the officers confronted him.

He fired at them, and the officers fired back, killing him, Lee said.

The violent string of events took less than 15 minutes.

Jenkerson called Riggins "a super gentleman at all times" who died doing "what St. Louis City firefighters do best: helping people."

"He was always there to help anybody," Jenkerson said.

St. Louis Mayor Francis Slay called Riggins' death a terrible tragedy, and compared it to other recent deaths of those who serve society.

"We couldn't live our lives without them," said Slay.

Riggins is at least the fifth local emergency responder killed by gunfire this year.

On Friday, University City police Sgt. Michael King was slain by a gunman as he sat in his parked patrol car.

Maplewood firefighter Ryan Hummert, 22, was killed in a July 21 ambush, a shooting that also left two Maplewood police officers injured.