A 25-year-old gunman shot a staff member at a Baltimore high school on Friday, authorities said. The suspect was taken into custody and the school was placed on lockdown.

Police said a 56-year-old hall monitor confronted the gunman in the school's entrance. A confrontation ensued, and the gunman shot the older man. The victim is in serious but stable condition at a local hospital, police said.

The suspect was apprehended by police within minutes. Police said he did not make it into the school before his arrest.

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All of the students are safe, and classes would be dismissed early so police could continue their investigation, Baltimore City Schools said.

Students told CBS Baltimore they saw classmates running down the hallway after the shooting. Others said they didn't witness anything.

Maryland Gov. Larry Hogan said he was closely monitoring the situation. "The state stands ready to provide any support necessary to the school, community, law enforcement, and first responders," Hogan tweeted.

This story is developing. Please check back for updates.