Trivia: Leon Kennedy, a popular character from the games, was originally intended to be in the film but was dropped. He later appeared in the fifth film.
Trivia: Wentworth Miller's first line in this film is "I know a way out of here." Almost identical to his famous line in Prison Break. (00:40:30)
Answer: Based on the sounds to go with the scene, I'd say it is zombies taking the guards out. However, considering following events it is more likely that Alice and her friends have something to do with it.