Nine people were taken to Denver area hospitals after a rollover bus crash on Peña Boulevard, a Denver Police Department spokesman said.

#TRAFFIC: #DPD investigating a single vehicle, rollover crash at outbound Pena Boulevard and 78th. Three parties transported to the hospital, conditions unknown. #Denver pic.twitter.com/VnUom8qp53 — Denver Police Dept. (@DenverPolice) December 18, 2017

The accident involved a bus that belongs to The Parking Spot, an airport parking service, police spokesman Sonny Jackson said. The accident happened near Peña Boulevard and East 78th Avenue, shutting down some lanes as emergency workers responded.

The accident snarled traffic on Peña Boulevard, causing delays for people trying to get to Denver International Airport. All lanes had reopened by 4 p.m.

None of the people taken to the hospital suffered life-threatening injuries, according to the Denver Police Department Twitter account.

Traffic investigators are in the early stages of figuring out what happened, Jackson said. They are interviewing witnesses at the scene.

“We don’t have a clear picture of what happened just yet,” Jackson said.