DENVER (AP) — A police officer who was one of three people killed in a shooting at a suburban Denver shopping district was a school resource officer known for developing relationships with students, city officials said.

Police have not explained what started Monday's shootout that also killed a suspect and a man they described as a “Samaritan” near a library in downtown Arvada that is home to popular shops, restaurants, breweries and other businesses about 7 miles (10 kilometers) northwest of downtown Denver.

Authorities were expected to disclose more information about the shooting Tuesday afternoon. They have not made public the identities of the other two people who died.

With school out for the summer, officer Gordon Beesley was working on patrol when police said he was hit by gunfire shortly after a report of a suspicious incident that they have not described.

Beesley worked for the Arvada Police Department for 19 years as a patrol officer and as a motorcycle traffic officer before being assigned to work with students at Oberon Middle School.

According to his school resource officer biography, he played the drums in a band and enjoyed hiking, biking, skiing, and camping with his family. His motto was “Look for the good in every day.”

In 2015, Beesley began biking to school alongside a seventh grader with developmental delay after learning that he was really interested in bicycles but that his mother did not want him riding alone, according to a KUSA-TV story.

The shooting in Arvada came three months after a gunman opened fire and killed 10 people, including a police officer, at a supermarket in Boulder, about 20 miles (32 kilometers) northwest of Arvada.