The Broward County Sheriff’s Office said it is investigating allegations that multiple deputies failed to enter Marjory Stoneman Douglas High School in Parkland, Fla., after the shooting rampage there, adding to the mounting internal probes examining both the department’s response to the attack and its prior interactions with the suspected shooter.

Authorities have faced criticism about the series of unheeded warning signs that preceded the Feb. 14 massacre. These warnings about Nikolas Cruz, the 19-year-old charged with the massacre, included multiple tips saying he could be capable of carrying out a school shooting. The FBI received such a tip in January but never investigated it. The Broward County Sheriff’s Office said it received two similar warnings, but there is no evidence that either prompted any investigation.

Officials have also faced difficult questions about what happened after the shooting began inside Stoneman Douglas. Broward County Sheriff Scott Israel acknowledged Thursday that an armed deputy, serving as the school resource officer at Stoneman Douglas, got to the scene of the shooting but failed to go inside, violating accepted police protocol. That deputy, Scot Peterson, a three-decade veteran of the sheriff’s office, resigned after being suspended.