The incident began at 5:40 a.m. with a report of a pickup truck fire in Maplewood, a suburban town just southwest of St. Louis. When firefighters arrived, someone began firing shots.

St. Mary's Hospital spokesman Eric Clark said a firefighter/paramedic from Maplewood was killed. The city identified him as 22-year-old Ryan Hummert. Officials said he was shot to death as he got off the fire truck.

Hummert, the son of former Maplewood Mayor Andy Hummert, began his career in August 2007 after graduating from paramedic training. He graduated from the St. Louis County Fire Academy in March.

"He had been with the fire department for only 10 months but knew it was his calling," Fire Chief Terry Merrell said at a brief news conference as he fought back tears. "It's impossible to say in words the emotion and pain we are feeling right now."

A Maplewood police officer also was taken to St. Mary's Hospital, where he was being treated for a gunshot wound to the right shoulder. Clark said his injury was not considered life-threatening.

The third injured emergency worker was taken to another hospital. There was no immediate word on his condition.

Besides the burning truck, a house across the street was on fire. The suspect was believed to be inside the house. Dozens of police officers from Maplewood and nearby communities surrounded the brick bungalow, pointing their rifles at the home as smoke poured from it.

Around 10:30 a.m., the fire suddenly intensified and loud popping sounds could be heard, neighbor Lamira Martin told KSDK-TV.

"Oh my God, the windows are blowing out," Martin told the TV station.

Sanyoz Rai, who works at a 7-Eleven store nearby, said he heard three or four shots at around 5:45 a.m., then saw a police officer go to the ground holding his shoulder. Rai said he then saw a firefighter on the ground behind the truck. He said the firefighter remained there for an hour before authorities could get close enough to remove him