One day after 75 vehicles were caught up in a series of crashes on Interstate 95 that injured at least 17 people, state police were trying to determine the sequence of events that led to the chain-reaction collisions.

The pileup – believed to be the largest crash in state history – began just after 7:30 a.m. Wednesday and stretched from Carmel into Etna.

No charges had been filed on Thursday in connection with the crashes, the Maine State Police said.

“The troopers are now going through the paperwork as a result of a multitude of crashes,” Department of Public Safety spokesman Steve McCausland said in a statement. “They’re continuing to interview the motorists involved and are also looking at photos that they took on the scene to try to get a sequence of events that lead to the chain reaction.”

The investigation will examine the sequence of events to determine why so many cars ended up involved in the crashes, which occurred amid heavy and wet snowfall that made for poor visibility.

Troopers are looking into reports that the pileup began when a single car went off the road and another motorist stopped to lend a hand.

“We have heard that, but have not confirmed that,” McCausland said.

While State police said 17 people were injured, hospital officials in Bangor reported treating more than 20 people.

The emergency department at Eastern Maine Medical Center saw 14 patients on Wednesday, five of whom were admitted and stayed overnight, spokeswoman Amanda Feero said. Two other patients were treated after arriving at the hospital on their own. Nine patients were discharged, and the others ranged from good to serious condition.

St. Joseph Hospital, also in Bangor, treated six crash victims on Wednesday, according to Amy Kenney, director of communications. One of them was admitted overnight, four were treated and released, and one was transferred to EMMC.

The Maine Department of Transportation also is gathering data to evaluate the crash, department spokesman Ted Talbot said. Dozens of transportation workers will examine information about conditions that include the snowfall, vehicle speeds, ground and air temperatures.

The department collects such data frequently during the winter, and Talbot expects to have the information related to the pileup assembled by early next week.

“It’s where we try to piece together not only what happened, what the current conditions were, but is there something we can learn?” Talbot said.

Talbot said one clear factor is that stretch of the highway in Etna has historically had different weather patterns “that happen to move through there, where there haven’t been in other areas.”

“I think the condition of the road is fine. It’s what happens with the precipitation,” he said. “So, we’ll be looking at visibility and how heavy the snowfall was. We want to look at all the conditions, both atmospheric and ground level, and get all the facts and understand if we can do anything better.”

Police investigators also will look into whether a change in driving habits could prevent a similar accident.

So far in February, there have been pileups during snowstorms involving 25 or more vehicles in New York, Pennsylvania, Ohio, Massachusetts and Chicago. Last month, there was a 35-car pileup on Interstate 93 in New Hampshire during a snowstorm.

McCausland said the state police begin every winter season and every pending storm with a reminder to motorists to go slow on ice and snow.

“If there is a teaching moment that comes out of this, we will make those facts known,” he said.