Three people were killed and nine others were transported to the hospital from what is believed to be an accidental car crash at an auto auction in Massachusetts, officials said.

The crash at the Lynnway Auto Auction in Billerica, about 24 miles northwest of Boston, happened at 10:13 a.m. when the driver of a 2006 Jeep Grand Cherokee waiting to enter the auction suddenly accelerated and entered the building at a very high rate of speed, officials said at a news conference this afternoon. The driver has been identified by officials as a male in his 70s who is an employee of Lynnway Auto Auction.

Several hundred customers were inside the building and a few hundred customers were outside the building at the time, officials said.

Two women and one man died, officials said. Six people remain hospitalized, one with life-threatening injuries, officials said in a press release this evening.

The Massachusetts State Police said in a news release that authorities believe the incident was an accident.

"At this point, there is no evidence or information to suggest the incident was caused by an intentional or terrorist^[1] act. All evidence and information at this time suggest an accidental cause," the release stated.

The investigation is ongoing, police said. Several people witnessed the incident, and one described it as "horrific."

"We heard a bang or an explosion. It was almost like a bomb. The whole place just went silent," said auction attendee Randy Miller, according to ABC affiliate WCVB in Boston. "There were people just lying on the ground -- a horrific, crazy, tragic situation."

The incident is being investigated by the Middlesex District Attorney's Office, the Billerica Police Department and the Massachusetts State Police CARS unit.

ABC News' Will Gretsky, Aaron Katersky and Courtney Connley contributed to this report.