PHILADELPHIA (CBS) — Police say a mother and her three young sons were struck and killed by a vehicle on the Roosevelt Boulevard Tuesday night.

The woman’s fourth son was injured.

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The accident happened at about 10:20 p.m. at Roosevelt Boulevard near Rockland Street in Feltonville.

Chopper 3 HD was over the scene as multiple police and rescue units responded.

Philadelphia police say a 28-year-old mother and her four sons were crossing Roosevelt Boulevard when they were struck by a vehicle at the same time.

According to investigators, the mother and her 23-month-old son were pronounced dead at the scene.

A seven-month-old boy was rushed to Albert Einstein Medical Center, but was later pronounced dead.

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A four-year-old boy was transported to St. Christopher’s Hospital for Children and was pronounced dead at 4:45 a.m. Wednesday.

A five-year-old was taken to the hospital with bumps and bruises, and was later released.

Police say the 23-year-old driver, operating an Audi, remained at the scene.

He was taken to Philadelphia Police Headquarters for questioning.

Investigators are looking into eyewitness reports that the driver may have been drag racing, but that has not been confirmed.

The southbound inner lanes of the Roosevelt Boulevard were reopened at about 6 a.m. Wednesday.

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