One person was killed and 17 were injured after a man plowed a car into a crowd that had gathered for a community fundraiser in eastern Pennsylvania this weekend, authorities said. He then drove to a neighboring county to fatally attack his mother, leaving investigators searching for a potential motive.

Police on Sunday identified the suspect at both crime scenes as Adrian Oswaldo Sura Reyes, 24, and said he had been arraigned on two counts of criminal homicide. Reyes was denied bail and sent to the Columbia County Correctional Facility, police said.

Shortly after 6 p.m. Saturday in Berwick, Pennsylvania, a car plowed into a crowded event that was raising money for the families of 10 people killed in a fire in neighboring Nescopeck. Reyes, authorities said Sunday, then drove to Nescopeck, where he hit his mother with a car and bludgeoned her with a hammer. Rosa D. Reyes, 56, was pronounced dead at the scene, according to an autopsy report from the Luzerne County Coroner's Office.

"This is a complete tragedy in a community where there's already been tragedy," state trooper Anthony Petroski said at a news conference. "We are going to do our job to the best of our abilities to conduct a thorough investigation not only for the families but for the community members."

Law enforcement officers arrived at the fundraiser to find several people injured and one dead. Petroski would not say whether the driver may have struck the eventgoers intentionally.

Authorities have not named the people injured or killed at the benefit. Geisinger Medical Center had treated 15 patients across several of its locations, spokesman Matt Mattei said early Sunday. Eight remained hospitalized at the Danville facility, with five in critical condition and three in fair condition. Four others had been treated and released.

Three patients were treated at other Geisinger hospitals and released.

The house fire in Nescopeck began in the early morning hours of Aug. 5 in a two-story home. Among those killed were three children who were 5, 6 and 7 years old, according to Pennsylvania State Police. Among the firefighters who responded was Harold Baker, who lost relatives in the blaze.

Community members Saturday rallied together to offer what they could at Intoxicology Department, a bar in Berwick. In the lead-up to the fundraiser, the bar posted a steady stream of updates on Facebook: A radio station would broadcast the benefit, musicians would provide live entertainment and locals would sit in a dunk tank.

"It's going to be an amazing day!" said a post written as the event got underway.

Then, the community was rocked by more tragedy.

Bar owner Lauren Hess said she is friends with two mothers whose children were killed.

"It was immediately, what can I do to help?" she told the station. "They're going through so much grief and pain."

Footage from the early hours of the event showed people laughing and lobbing water balloons at one another as music played in the background.

Then, at about 6:15 p.m., state police got a call from the Berwick Police Department about a car driving through the event, Petroski said.

Photos of the aftermath showed personal items strewn on the ground near tents and tables that had been set up for the day's festivities. Intoxicology Department posted a statement on Facebook saying it would be closed until further notice: "Today was an absolute tragedy. Please respect our privacy while we grieve and try to process the events that occurred. Thank you."

After Reyes was detained, reporters recorded video of police escorting him early Sunday. Asked whether he had anything to say, he offered: "Sorry, I'm sorry."