WPVI-TV reports ( http://bit.ly/VNKCC7) it happened around 10:30 p.m. Sunday at the Snug Harbor Marina in Croydon, about 20 miles north of Philadelphia.
Investigators say the boats went up in flames after some sort of explosion, but there weren't any injuries. Firefighters were eventually able to get the blaze under control.
A cause has not been determined.
Information from: WPVI-TV, http://abclocal.go.com/wpvi