Police and prosecutors in Seattle are preparing subpoenas requesting footage of the violent May Day protests from television stations in the area, according to the Seattle Times.

Tuesday’s protests turned violent and resulted in widespread vandalism in downtown Seattle. Footage shot by television stations could be used to identify suspects, the Times reports:

The state’s “reporter shield law” limits law-enforcement access to unpublished material gathered by journalists, but three network-affiliated TV stations contacted Tuesday said that with a subpoena they would turn over footage that already had aired.

Holly Gauntt, KOMO-TV news director, said one clip the station aired shows a black-clad protester changing into street clothes. “There’s one shot we have where you can clearly see the guy,” she said.

A veteran photographer for KING was injured while covering the protests for the NBC-affiliate.

Watch KOMO’s report on the violence after the jump.