PLEASANTON -- Firefighters battled two blazes on freeway onramps early Monday, including one caused by fireworks, according to the Livermore-Pleasanton Fire Department.

The two fires were reported at 1:20 a.m., the first located on the onramp from Bernal Avenue to southbound Interstate-680 and the second on the onramp from Sunol Boulevard to northbound Interstate-680, according to Battalion Chief Michael Miller.

The Bernal Avenue fire burned a 50-foot by 50-foot area and was quickly extinguished, according to Miller. The cause of the fire is undetermined. The Sunol Boulevard fire, which was caused by fireworks, burned one-quarter acre before it was extinguished, Miller said.

David DeBolt covers breaking news. Contact him at ddebolt@bayareanewsgroup.com. Follow him at Twitter.com/daviddebolt.