The young man called his mom Saturday night to say that he had arrived safely at his destination in the District. She recalled that he finished the conversation by telling her that he loved her.

In less than an hour, according to a D.C. police account, Darnell Ross, 20, who lived in Upper Marlboro, was struck by a car and killed. Police said the vehicle did not stop after Ross was struck about 10:30 p.m. in the 100 block of M Street NE.

“I would like for them to find the person who hit my baby,” Ross’s mother, Cassandra Ross, said Sunday night. She said she hoped the motorist would come forward.

The police said Ross had fallen while in a crosswalk. The location is about three-quarters of a mile north of Union Station in the fast-developing area known as NoMa.

His mother said he was going to a club.

“He called me about 10 and let me know he had gotten there,” she said. “He told me he loved me.”

Darnell Ross graduated from Dr. Henry A. Wise Jr. High School and attended Prince George’s County Community College, his mother said. He worked as a home-care provider for people with mental and physical disabilities, she said.

Ross was the third pedestrian to be killed in the District last week. A fourth was killed in Montgomery County. Police accounts indicated that motorists had remained at the scenes of the other incidents.