WALNUT CREEK -- Security camera footage at a private school helped police capture a man they say committed a lewd act in front of a student on the campus.

Police on Friday arrested 39-year-old Darryl Allen of Walnut Creek on suspicion of indecent exposure, committing a lewd act with a child under 14 and annoying or molesting a child under 18, according to a police news release.

The arrest came a day after police were called to Walnut Creek Christian Academy on Buena Vista Avenue to check on a person who was reported to be trespassing on school grounds, police said. Officers checked the area but were unable to locate anyone.

But school officials reviewed security camera footage Friday that showed a man confronting a student on campus and committing a lewd act in front of the minor, police said. The student immediately ran away, police said.

Police identified Allen, who police said lives near the school, as the suspect. He was contacted at his home and arrested.

He was taken to County Jail in Martinez, where he was being held on $145,000 bail.

The student was not physically harmed, police said.

Rick Hurd covers crime. Contact him at 925-945-4780 and follow him at Twitter.com/3rdERH.