A natural gas leak at 7:18 a.m. on Monday led to the temporary closure of the Seeley G. Mudd (SGM) and Irani Hall (RRI) buildings, according to USC Fire Safety & Emergency Planning. There were no injuries.

A construction vehicle working on the Michelson Center for Convergent Bioscience hit a gas line, causing the leak. The incident occurred on McClintock Avenue near Downey Way. USC's Entrance 6 was closed, so drivers planning to park in Parking Structure A had to enter the campus via Entrance 1, off Exposition Boulevard.

The Los Angeles Fire Department said that there was no fire and the evacuations were "calm and orderly without injury."

According to USC Fire Safety expert Steven Goldfarb, the leak had been stopped by 8:50 a.m., gas levels in the air had returned to safe levels and buildings re-opened. SoCalGas said it was continuing to make repairs to the two-inch line that had been damaged.

"At no time was air quality at a point where we needed to do any other evacuations," Goldfarb said.

Reach Staff Reporter Aaron Glazer here, or follow him on Twitter.

Staff Reporters Misa Buscemi, Rose Poole, and Trevor Sochocki contributed reporting.