CAIRO — Gunmen drove into Cairo’s Tahrir Square before dawn Monday and fired at an antigovernment sit-in, seriously wounding a protester who had been jailed and tortured by former military rulers after he witnessed the killing of another activist. Two lawyers involved in the case suggested it was a targeted attack.

Lawyer Tamer Gomaa identified the wounded activist as Muhanad Samir, 19, and said he was battling for his life with a number of pellets embedded in his skull and in his face.