A late-morning run by the Boston Fire Department turned into a spectacular collision Monday that left four firefighters and a driver injured, and a series of parked cars in a mangled mess.

Fire Commissioner Joseph E. Finn said the four firefighters were aboard Engine 7 responding to an alarm at 11:26 a.m. when they struck a Chevrolet Equinox SUV that got in their path at Dartmouth Street and Commonwealth Avenue.

The crash ripped the hood off the Equinox and caused the firetruck to plow into a pair of parked vehicles, resulting in a domino effect that left cars pressed into each other.

Engine 7 left its firehouse on Columbus Avenue in Park Square and had its lights and siren going as it responded to a fire alarm that had activated at 1120 Boylston St., fire officials said.

The Equinox drove into the intersection as the fire truck approached. It was unclear why, officials said.

Kaitlin Stratton, who was waiting with her parents at 127 Commonwealth Ave., said she saw the firetruck approaching the intersection just before the crash.

Her father screamed at the truck. “Stop driving!’’ she recalled him saying.

It was too late.

“That’s when everything blew up,’’ she said. “The firetruck swerved, flew, and then hit the cars.’’

The Bay State College student said she thought the firetruck was going to crash into a building, but it landed atop cars. She said she and her parents raced to the SUV, and she opened the passenger door. A man at the wheel opened the driver’s side, spilling onto the pavement.

“I think he was unconscious,’’ she said.

He came to later. Her mother, she said, tended to him until EMTs arrived. Stratton said that her mother is a nurse.

Linda Zukowski, who lives across from the crash site, said she was in her living room when she heard a loud bang. “I just happened to get up and see the tree fall and the firetruck,’’ she recalled.

None of the five suffered major injuries, said Finn, who did not identify any of those who were hurt. They were taken to Massachusetts General Hospital, he said.

He said the firefighters had “some pretty good bangs’’ and other injuries.

Police will reconstruct the accident. There is a camera at the intersection. Officials from the Boston Police Department did not respond to a request for information.

The wrecked SUV rested near a sidewalk. The firetruck was also severely damaged.

It was unclear how fast the firetruck was going. Firefighters have no restrictions on how fast they should drive in response to an emergency, Fire Department spokesman Steve MacDonald said. The time of day, traffic, and experience driving in emergency situations factor into fire crew response, he said.

“Firetrucks are driven at [speeds] the operator thinks are safe while responding’’ to an emergency, MacDonald said.

Police investigators had not been able to talk to the SUV driver or the firefighters Monday afternoon because they had been taken to the hospital, MacDonald said.

The firefighters were responding to a “smoke in the building’’ call at 1120 Boylston St., which is in the Fenway. It turned out that the alarm was triggered by dust caused by workers in the basement of that building, MacDonald said.

For firefighters leaving their station in Park Square, going down Commonwealth Avenue would have been the most direct way to get to the Fenway.

Meghan E. Irons can be reached at meghan.irons@globe.com.