A Colleton County inmate awaiting transfer to prison attacked a guard at the county jail and briefly escaped Sunday, authorities said.

Mack Washington Jr., 31, was sentenced last week to 35 years in prison for robbing an elderly couple at knifepoint. He got loose from the jail about 5:15 p.m. Sunday, Colleton County Sheriff's Lt. Amye Stivender said. Dogs were brought in to track him down, and he was taken back into custody about 30 minutes later.

The guard was not seriously hurt, she said.

Washington was convicted of robbing a couple in their 80s in January 2012 at the Rice Planter's Inn. He held a knife to the woman's throat and threatened to kill her if she didn't hand over her valuables, then made off with their car.

Washington's previous convictions before this robbery include four counts of burglary, four counts of strong-arm robbery, accessory before the fact of strong-arm robbery, driving under suspension, resisting arrest and giving a false name to law enforcement, according to prosecutors.

Washington has to serve at least 85 percent of the sentence before he is eligible for parole. There was no immediate word on whether his latest caper will add to his sentence.

Reach Dave Munday at 937-5553.