Orlando, Florida (CNN) -- Authorities were searching Friday for a man described as "armed and extremely dangerous" after at least seven people were shot in an Orlando office building where the suspect used to work, a fire department spokeswoman said.
Fire Commander Vicki Robles said seven people were shot and in "extremely critical" condition. An eighth person had cardiac-related problems, she said.
Robles said authorities were searching for Jason Rodriguez, who formerly worked for Reynolds Smith and Hills in Gateway Center in Orlando.
A spokesman for Reynolds Smith and Hills, a facilities and infrastructure consulting firm, said a former employee let go for performance issues came in Friday morning "and started shooting."
Mike Bernof said the employee, whom he did not name, was let go in June 2007.
Bernof provided no other details.
Police cordoned off the area as SWAT teams searched the 16-story building while a sheriff's department helicopter circled overhead.
The office tower, which is adjacent to the Sheraton Orlando Downtown hotel, lies beside Interstate 4 and Lake Ivanhoe on the northern edge of downtown.
Investigators are looking for a man wearing a blue Polo shirt, gray vest and blue jeans, according to Jim Solomons, a spokesman for the Orange County Sheriff's Office, which is helping the city police department.
"We're in a search mode for the gunman," he said.
Sgt. Barbara Jones of the Orlando Police Department said there were multiple victims but would not confirm a number or their status.