A gas station employee was injured in Silver Spring on Friday morning during a robbery attempt, causing nearby Montgomery Blair High School to lock its doors while police looked for a suspect.

Mongtomery County police initially said that the victim had been shot, and Capt. Paul Starks said he was in “very serious” condition. Starks later said that the victim had in fact been struck in the head with a handgun, not shot.

Police said that they received a call about a robbery at the Shell gas station at the intersection of University Boulevard and Route 29 at 6:35 a.m. Two minutes later, they got a call reporting a shooting.

The busy intersection was not closed, but traffic was clogged as police filled the area. Metrobuses on numerous routes were delayed.

As students arrived at the high school, which starts the school day at 7:25 a.m., police escorted them into the building, school district spokesman Brian Edwards said.

Students waited in the auditorium and gymnasium while police searched the hallways, bathrooms and other areas of the school to make sure the suspect was not inside, Starks and Edwards said.

Classes finally started for the day at about 10 a.m.

Police said that they are looking for one suspect, a white or Hispanic man, about 5-foot-8 or 5-9 wearing a black jacket and black pants, who was on foot when he left the gas station.