WOODBRIDGE -- The quick thinking of a 5-year-old boy helped protect his mother from getting robbed, police said.

The incident happened Monday afternoon in a grocery store parking lot in the 2000 block of Daniel Stuart Square in Woodbridge, said Officer Erika Hernandez, Prince William police spokeswoman.

A 26-year-old woman from Big Stone Gap was securing her three children in her van when a man approached her and asked for money, Hernandez said.

When she refused, the man attempted to grab the purse from her, police said.

A scuffle ensued, but the woman was able to get herself and the purse into the van.

The 5-year-old then locked the doors, Hernandez said, thwarting the would-be robber's attempts to force his way into the van.

Police responded to investigate a burglary in progress, Hernandez said, and a policeman arrested a suspect a short distance away.

Kenneth D. Sweetman, 34, of no fixed address, was taken into custody and is being held at the Prince William-Manassas regional jail in lieu of a $500,000 bond, police said.

Sweetman was charged with attempted strong-arm robbery, public intoxication, assault and battery on a police officer and two counts of obstruction of justice.

Sweetman is accused of assaulting one of the police officers and making physical threats against the officer and the magistrate.

He is scheduled to appear in court June 24, Hernandez said.