Sonoma County sheriff's detectives still were searching Thursday night for a man who held up a northern Santa Rosa bank during the noon hour.

The robbery, at the Exchange Bank branch in Larkfield, was reported at 12:23 p.m, sheriff's Lt. Al Vernon said.

A search involving several deputies, Windsor officers, police dogs and the sheriff's helicopter quickly got underway. But the man wasn't found and after about 90 minutes, the search was suspended.

Sheriff's detectives released a photograph of the suspect Thursday night that was taken from the bank's surveillance video.

It shows what the Sheriff's Office describes as a slender white male in his 20s, between 5-feet-8 and 5-feet-11 inches tall, with a brownish patch of hair under his bottom lip. He was wearing a tan or green long-sleeve button-up shirt, black pants and light-colored shoes, a camouflage beanie cap and dark sunglasses.

The busy bank branch is in the Larkfield Shopping Center on Old Redwood Highway near Mark West Springs Road.

The robber walked into the branch and demanded money, Vernon said. He was given cash, which he stuffed into a plastic grocery bag, then fled on foot. He was last seen running southeast through the Larkfield center parking lot.

Sheriff's officials did not say if the man had a weapon.

The search covered the rural residential hills behind Larkfield and reached into the nearby Wikiup neighborhood.

Three Mark West School District elementary schools were locked down after being contacted by sheriff's officials about the robbery.

Mark West Superintendent Ron Calloway said Mark West, San Miguel and Riebli schools went into lockdown, mainly through their lunch breaks.

The lockdown lasted from about 12:40 to 1:30 p.m. At that point, sheriff's officials called the school district to say they could resume normal class activities.

"We've been released," Calloway said, contacted just after 1:30 p.m.

School district officials also had contacted other schools in the area, including Cardinal Newman High School and adjacent Roseland Collegiate Prep, to alert them to the search, the superintendent said.

Business owners and employees in Larkfield said the business area was swarming with patrol cars while the helicopter circled.

Exchange Bank is offering a $5,000 reward for information leading to the arrest and conviction of the suspect. Sheriff's officials did not say how much the man was reported to have taken.

Anyone with information is asked to call the sheriff's investigations bureau at 565-2185.

(Elizabeth M. Cosin contributed tothis story. You can reach Staff Writer Randi Rossmann at 521-5412 or