HANOI, Vietnam — Nearly 600 inmates in a Vietnamese drug rehabilitation camp overpowered security guards and escaped, an official said Monday. At least two-thirds of them were still at large. Trinh Vuong Thuan, a security official at the rehabilitation center No. 2 in the northern port city of Haiphong, said 578 inmates overpowered security guards to break through the center's gates on Sunday. Vietnam's strict laws on drugs allow the government to order addicts held for up to two years in rehabilitation centers, many of them boot-camp-style camps that include hard labor and communist "ideological education." The uprising and escape started when an inmate called on others to flee while they were having dinner, he said. "We were completely overwhelmed," Thuan said.