San Francisco's Lefty O'Doul Bridge, also known as the Third Street Bridge, is closed Tuesday evening after two barges apparently came unmoored in high winds and struck it.

At 5:44 p.m., the San Francisco Fire Department tweeted photos that show two barges pushed against the bridge, which spans Mission Creek, the narrow body of water that separates SoMa from Mission Bay. The pedestrian walkway, which consists of wooden planks, has been splintered in one section. The railing was also damaged, but there are no reports about the roadbed or the massive concrete counterweight, known as a bascule, that enables the bridge to open to ships.

The barges appear to have been further out in San Francisco Bay before heavy surf pushed them toward the shoreline. It is not known at this time if any injuries have been reported, either on the vessels or ashore.

Although short, the 90-year-old bridge is a major thoroughfare leading to Downtown, just near AT&T Park. Multiple lanes of the much more heavily used Bay Bridge remain closed after a big rig overturned on the eastbound section this afternoon.

This is a developing story.