State police say the investigation into a 70-car pileup that injured at least 17 people on a snowy interstate in Maine could take a while.

Police say the pileup on Interstate 95 began in Carmel and Etna at about 7:30 a.m. Wednesday when the vehicles became entangled in chain-reaction crashes caused by snow and speed.

State police say the crash was the biggest in Maine in more than 15 years.

Lt. Sean Hashey says investigators may never determine exactly how the events unfolded because of how many vehicles were involved. He did not rule out the possibility of criminal charges.

The accident closed a northbound stretch of the highway for about five hours near the Bangor area.