House Speaker Nancy Pelosi (D-Calif.) announced Thursday that she will create a House select committee to investigate the Jan. 6 Capitol attack after Senate Republicans blocked legislation to create a 9/11-style bipartisan commission last month.

The announcement comes with “great solemnity and sadness,” Pelosi told reporters. Investigators will have “as long as it takes.”

“Again, January 6 was one of the darkest days in our nation’s history,” she said. “It is imperative that we establish the truth of that day and ensure that an attack of that kind cannot happen [again] and that we root out the causes of it all.”