HAYWARD -- Hayward police Friday released the sketch of a man suspected of attacking and sexually assaulting a woman early Sunday morning.

Police responded at about 3:40 a.m. to a 911 call from a residence in the 24400 block of Alves Street, the Police Department reported. Arriving officers located a 30-year-old woman who said she had been sexually assaulted on a walkway that crosses over Bay Area Rapid Transit tracks between Sycamore Avenue and Whitman Street, according to police.

The woman reported that she had been walking west on the walkway approaching the spiral staircase leading down to Whitman Street when the suspect attacked her from behind, according to police. The suspect allegedly forced the victim onto the ground and sexually assaulted her.

The victim ran to a residence after the attack, where she called 911, police reported. She was taken to the hospital for treatment and released.

The suspect, who was last seen fleeing eastbound on the walkway toward Sycamore Avenue, is described as a black man in his early 30s standing between 5 feet 8 inches and 6 feet tall and weighing between 150 and 170 pounds.

The suspect was last seen wearing a dark colored beanie with a short brim and a tan or light colored jacket with jeans, police reported. He may have dark cropped hair.

Hayward police ask that anyone with information regarding the incident contact the Hayward Police Department Investigations Hot Line at (510) 293-5037 or the Crime Stoppers of Southern Alameda County Hot Line at (510) 293-7197.