SAN FRANCISCO — Two men charged with tying up employees at gunpoint during a cellphone store robbery made a dramatic escape Monday from a suburban Silicon Valley courthouse, fleeing in a car waiting outside for them, officials said.

The escape by Tramel McClough, 46, and John Bivens, 47 appeared to be orchestrated and investigators were trying to determine how they got away from a sheriff's deputy who had been guarding them, the Santa Clara County Sheriff's Department said in a statement.

The two, who are considered dangerous, escaped from the deputy after they left a courtroom where McClough and Bivens had been brought for a hearing, said Sgt. Reggie Cooks.

Cooks said the two jumped into the waiting car, which they abandoned a few blocks away for a U-Haul moving van. People were asked to call police if they see them but not to approach them.

"The level of sophistication and brazenness it takes for the individuals to do that — that is why we're calling on the public and other allied agencies to help," Cooks told reporters.

The Palo Alto police department said on Twitter that there was no search for them in the city, which is home to numerous technology companies and Stanford University. The two men live in neighboring East Palo Alto.

Officials said the they were held without bail after robbing a Verizon store of $64,000 in merchandise in February. Police have said they tied up the store employees, forced one to open a safe and were arrested a short time later after a car chase.

The escape is the latest setback for the Santa Clara Sheriff's Department, which runs the county's jails and is responsible for escorting inmates to and from court.

Four inmates escaped from the county's main jail last year by cutting through metal bars and rappelling to freedom using a rope made of clothing and sheets.

Last month, a clerical error mistakenly released an inmate from jail on the day he was sentenced to an 8-year prison sentence for armed robbery. He was captured a week later.

In June, three former jail guards were convicted of murder for beating a mentally ill inmate to death in 2015.