Two people were killed and 19 others taken to hospital following a major crash in Lincoln, Nebraska, police said Monday. The incident appeared to unfold as an “Americruise” event was taking place.

The Lincoln Police Department said in a tweet at around 1:30 a.m. ET Monday morning that officers were investigating a “fatality accident” after receiving initial reports of multiple vehicles crashing into a large crowd.

It later said two “female occupants” had been killed in the incident, with 19 others transported to hospital. Of those, police said one was in critical condition and the other 18 people were believed to be in non-life threatening condition.

The ages and identities of the deceased were not immediately clear. Police did not immediately respond to a request for more information.

In a call with dispatchers published by Broadcastify, a first responder can be heard describing “people laying in the street” after being hit by a vehicle. The responder said several people were “down” and that at least one vehicle had flipped.

They also warned of “trapped occupants” in a car that had started to catch fire.

Police said the incident had unfolded near 52nd and O Street, where an “Americruise” event appeared to be taking place. It was not immediately clear whether the deadly incident was connected to the event.

Hosted by the Midwest Association of Car Enthusiasts, the “Americruise” saw drivers flock to Lincoln over Memorial Day Weekend to show off their cars by cruising down city streets.

“Every Memorial Day Weekend, hundreds of cars, bikes, and trucks flock to Lincoln, NE to cruise down O Street to show off their rides and do some hooning!” a Facebook page for the event said.

The event page also warned attendees of the risks of cruising down city streets.

“We want to remind everyone the police won’t be a stranger to this event so PLEASE cruise at your own risk and be cautious to those around you!” the event page says. “There will be large crowds all along O street and we don’t need anyone in a wreck or worse in the hospital!” it adds. NBC News has contacted the Midwest Association of Car Enthusiasts for comment.

In the days leading up to the event, police had warned about safety concerns connected to the annual event.

Kurt Chirbas and Colin Sheeley contributed.