A rock concert advocating freedom for Tibet was halted abruptly Saturday when a thunderstorm, with heavy lightning and pounding rain, hit the stadium filled with thousands of rock fans. At least 11 people were injured in lightning strikes, authorities said.

A District of Columbia fire department spokesman described the injuries as serious. A man bleeding from the mouth was seen being carried away on a stretcher.It was during one of the performances that a loud explosion brought a collective gasp from the crowd. Soon afterward, organizers began instructing fans to leave the field.

Some 120,000 screaming rock fans were gathered for the two-day concert, which is targeting President Clinton before he leaves in two weeks for a trip to China. Some of the rock stars plan to join a rally Monday outside the Capitol.