Pelosi says she will create a select committee to investigate the Jan. 6 assault on the U.S. Capitol.

Speaker Nancy Pelosi announced on Thursday that she would create a select committee to further investigate the deadly Jan. 6 attack on the Capitol, after Senate Republicans blocked a bipartisan effort to form an independent commission of experts to look into the riot.

“Jan. 6 was a day of darkness for our country,” Ms. Pelosi told reporters. “Our temple of democracy was attacked by insurrectionists.”

The move came after Ms. Pelosi had signaled for weeks that she planned to take such a step to scrutinize the storming of the Capitol...