PORTLAND, Maine — Hundreds of mourners marched in procession through the streets and attended a funeral Mass Saturday for a 27-year-old Sudanese immigrant who was shot to death last weekend while working as a hospital security guard.

People marched arm-in-arm behind a hearse carrying the body of James Angelo from a funeral home to the Cathedral of the Immaculate Conception, where they filled the church to near capacity. Along the way, they cried and sang and carried a portrait of Angelo, whose killing remains a mystery.

Angelo, a former youth soccer coach who hoped to one day become a police officer, was gunned down at about 4 a.m. last Sunday while working as a security guard at Mercy Hospital. He and his family moved from Sudan to Maine in 1995 to escape violence in their homeland.

At the church, members of the Sudanese community, Mayor Edward Suslovic and Bishop Richard Malone addressed the diverse crowd.

“There’s a very deep grieving process that is traditional in the Sudanese community,” said Glenn Cummings, a state representative from Portland who marched in the procession and attended the funeral service. “So there was a tremendous outpouring of grief at the service.”

On Friday night, more than 300 people attended a candle-light vigil for Angelo at the city’s Monument Square.

Police don’t have a motive in the shooting, but say they are working on some strong leads.

Video surveillance shows two people approaching Angelo at about 4 a.m. Sunday in a hospital parking lot and gunning him down as he turned away from them. Angelo, who was hit in his upper back near the base of his neck, died a couple of hours later at Maine Medical Center.

The hospital has offered a $20,000 reward for information leading to the arrest and conviction of those responsible for Angelo’s death.