Thousands of people are expected in downtown Portland on Tuesday for the funeral of a Maine State Police detective killed last week on Interstate 95 in Hampden.

Detective Benjamin J. Campbell, 31, had stopped to assist a motorist on April 3 when he was fatally struck by a tire that detached from a passing logging truck.

Police officers from across Maine and beyond are expected to attend Campbell’s funeral service Tuesday morning at the Cross Insurance Arena.

State police spokesman Stephen McCausland said representatives from 18 other state police and highway patrol agencies, along with members of the Royal Canadian Mounted Police, plan to attend the tribute to Campbell.

Campbell, who would have turned 32 Monday, is survived by his wife, Hillary, and their 6-month-old son, Everett. He joined the Maine State Police in 2012 and was promoted to detective in 2016.

Campbell, a member of the state police polygraph team, was on his way to a training session when the accident took place.

State police say that members of the public who plan to attend the service should park at the Maine Mall parking lot at 380 Gorham Road in South Portland. Beginning at 8:30 a.m., shuttle buses will take people to the Cross Insurance Arena.

After the service, people will walk to the Portland Fish Pier at the intersection of Center and Commercial streets, where buses will transport them back to their parking locations.

Portland officials announced that a number of local streets will be closed because of the service and warned drivers to expect extra congestion around the Cross Insurance Arena. Street closures will begin at 8 a.m. and last until 3 p.m.

Portland street closures include: Spring Street from High Street to Temple; Oak Street from Free to Spring; Center Street from Free to Commercial; Cross Street from Free to Spring; and Cotton Street.

Free Street will be closed from High Street to Temple for 30 minutes starting at 10:30 a.m. High and Commercial streets will be affected briefly during the day as a motorcade travels from South Portland to the arena.

Streets around the arena will be posted with emergency “no parking” signs starting at 6 a.m. Tuesday.