Shoes and slippers belonging to people attending Friday prayers lie near one of two mosques after an explosion that claimed more than 20 lives. Mohamed Azakir/Reuters

People inspect the damage inside one of two mosques hit by explosions in Lebanon's northern city of Tripoli, Aug. 23, 2013. Mohamed Azakir/Reuters

A boy receives medical treatment at a hospital after two powerful explosions hit Tripoli, Lebanon, on Friday. AFP/Getty Images

People gather after the blast outside al-Salam Mosque in Tripoli on Friday. AFP/Getty Images

The scene outside two mosques hit by explosions in Lebanon's northern city of Tripoli, Aug. 23, 2013. At Omar Ibrahim/Reuters

A crane removes burnt cars from outside one of two mosques hit by explosions in Lebanon's northern city of Tripoli, August 23, 2013. Sobhi Al-Sharif/Reuters

Residents gather around a crater caused by one of the two explosions outside one of two mosques in Lebanon's northern city of Tripoli, Aug. 23, 2013. Mohamed Azakir/Reuters

People gather at the site of a powerful explosion outside al-Salam Mosque, near former Lebanese police chief Ashraf Rifi's home, in northern Lebanon on Friday. AFP/Getty Images

Two car bombs in the northern Lebanese city of Tripoli on Friday killed 42 people and injured hundreds more, raising fears that the civil war raging in neighboring Syria could engulf Lebanon.

Ambulances rushed to the scene as heavy black smoke covered the sky, with television footage showing crushed cars and people carrying bloodied blast victims through the streets.

The blasts went off after Friday prayers near two mosques in the predominantly Sunni port city. A gun battle then broke out between nearby feuding neighborhoods of Jabal Mohsen, which supports Syria's President Bashar al-Assad, and the anti-Assad area Bab al-Tabbaneh.

The blasts come amid rising tension in Lebanon stemming from Syria's civil war, which has sharply polarized the country along sectarian and political lines.

Tripoli has endured clashes between Sunnis and Alawites, the minority sect to which Assad belongs. Lebanon's Shiite Hezbollah movement is a strong ally of the Assad regime.