Nine people died on Saturday in a “chaotic” traffic collision involving six vehicles in North Las Vegas, officials said.

“We have not seen a mass-casualty traffic collision like this before,” Alexander Cuevas, public information officer for the North Las Vegas Police, told reporters late Saturday.

Fifteen people had been involved in the incident, Cuevas said. Two were transported from the scene to University Medical Center, where one later died, he said. The other remained in critical condition, he said.

Officials said speed was a factor in the crash. It was unknown whether impaired driving had been a factor, they said.

A Dodge Challenger was driving north “at a high rate of speed” on Commerce Street prior to the crash, police said. Cuevas said witnesses saw the Challenger run a red light.

“And, with that, it struck multiple vehicles and, unfortunately, it was a chaotic event,” Cuevas said.

Several vehicles were pushed off the road into a vacant lot near the intersection of Commerce Street and Cheyenne Street, officials said. An emergency call was made just after 3 p.m. local time, Cuevas said.

The driver of the Challenger was among the dead, officials said. The deceased ranged from young juveniles to middle-aged adults, Cuevas said. Their identities will be released by the coroner’s office, police said.

“Our thoughts and our prayers are with the families who are experiencing a tremendous and unnecessary loss due to a careless, senseless act,” Pamela A. Goynes-Brown, a member of the North Las Vegas City Council, said.

This is a developing story. Check back for updates.