MIAMI (AP) _ A semitrailer cab rammed through four chain-link fences at an Everglades prison during a breakout Saturday before its driver pulled out a shotgun and started firing.

One man escaped and authorities say his mother planned the whole thing.

The woman and two of her accomplices were in custody; her son, who was believed to have been injured, escaped with the truck driver, police said.

Police were searching for Jay Junior Sigler, who had served eight years of a 20-year sentence for armed robbery. He was last seen at a shopping mall after switching cars with his mother and two of her accomplices, police said.

Sandra Sigler, 58, thoroughly thought out her son's escape from the Everglades Correctional Institute, about 20 miles west of Miami, said Miami-Dade detective Rudy Espinosa.

``By all accounts the mother masterminded everything,'' Espinosa said.

The truck barreled through the security fences about 3 p.m. The driver got out and started firing a shotgun at guards, Espinosa said. Two prison guards were treated for injuries they received while diving for cover.

Other guards returned fire and Sigler was believed to be hurt.

``We don't know if he is shot or what,'' Espinosa said.