Burglars broke through a roof and used a blowtorch to slice open a safe at a jewelry store in Oxon Hill, making off with $500,000 in merchandise, the Prince George’s County police said.

Police said the burglars “spent hours” inside the Rivertowne Jewelers on Oxon Hill Road in May while cutting a rough-edged square opening in a wall of the safe, burning through what appeared to be layers of metal and fireproofing.

A surveillance video excerpt was posted Friday on the police Web site to draw tips from the public, the police said.

The burglary technique appeared rare in this area. However, it bore strong similarities to burglaries reported in the last few years at jewelry stores around the country, including Ozark, Ala.; Davie, Fla.; and Philadelphia.