Gregory A. Hall at his home in Capitol Heights, Md. on November 15, 2012. (Marvin Joseph/THE WASHINGTON POST)

A Prince George’s County community activist and former drug dealer who unsuccessfully sought a seat in the Maryland State House died in a vehicle crash early Monday, authorities said.

Gregory Antoine Hall, 45, was driving westbound on Walker Mill Road in Capitol Heights about 2:50 a.m. when he was struck head-on by an eastbound SUV that had crossed into Hall’s lane of traffic, county police said in a statement.

Hall was pronounced dead at the scene. The driver of the striking vehicle suffered injuries that were not expected to be life-threatening, police said, as did the driver of another car, which the first vehicle sideswiped. Investigators are looking into whether alcohol or speed were factors in the crash.

Maryland politicians remembered Hall on Monday night as someone who had overcome a troubled past and used his experiences to encourage young people to make better choices.

“Greg Hall had made tremendous strides in his life,” said Del. Dereck E. Davis (D-Prince George’s). “We all knew about some of the difficulties he had, but he made tremendous strides in turning his life around, and he was doing good work in the community. He’s going to be sorely missed.”

In 1992, as a 21-year-old crack dealer, Hall took part in a gun battle that killed a seventh-grade honors student who was leaving church with his family. Hall was charged with murder and spent 40 days in jail. But the charge was withdrawn after ballistics tests showed that the fatal bullet came from a different gun. Hall was convicted of a separate, misdemeanor gun violation.

Since then, Hall had opened his own business, worked as an aide to then-County Council member William A. Campos (D) and become a well-known advocate for some of the county’s lowest-income neighborhoods.

In 2010, he ran for state delegate, losing the Democratic primary by a few hundred votes. Two years later, after first-term Del. Tiffany T. Alston (D) was ousted from office in a corruption scandal, the Prince George’s County Democratic Committee nominated Hall to replace her. But then-Gov. Martin O’Malley (D) rejected the nomination, citing Hall’s criminal past. Hall ran for delegate again in 2014 but lost in the primary.

Hall grew up in the Chapel Oaks neighborhood of Prince George’s, near the District border. He was indefatigable in keeping politicians accountable and was driven by a deep sense of fairness, said state Sen. Victor R. Ramirez (D-Prince George’s).

“He believed in second chances and wanted everyone to have the same opportunity to get ahead in life,” Ramirez said. “Greg was special and he was going to advocate for what he believed in. . . . In his own way, he pushed all of us to be better.”

Hall is survived by his wife, Jacqueline Marshall-Hall, principal of G. James Gholson Middle School in Landover, and five children — Ajalia Hall, Skylar Webb, Kalyn Upshaw, Bobby Marshall and Demetrius Brown — all of Maryland. Jacqueline Marshall-Hall said her husband had “touched the lives of many and will be greatly missed by all.”

Former state delegate Justin Ross, a longtime friend of Hall’s, said: “Greg loved Prince George’s and was very loyal to it, and the people who knew him admired that most about him. He was a voice for that part of town.”

Lynh Bui, Josh Hicks and Matt Zapotosky contributed to this report.