At least 100 inmates escaped on Monday from a maximum-security prison in Brazil's Paraiba state, officials said. A total of 33 of the 105 prisoners who escaped early on Monday were captured, the Paraiba Prison Administration Secretariat said. Some 20 men armed with rifles and explosives arrived at the prison in four vehicles and opened fire on guard posts, the barracks and the main entrance of the Romeu Gon\u00e7alves Abrantes maximum-security prison in Joao Pessoa, the state capital, Xinhua quoted the secretariat as saying in a statement. Guards and police engaged the gunmen in a shootout, the secretariat said, adding that the prison's main door was then knocked down, allowing 105 prisoners to escape. Another group of gunmen, meanwhile, blocked part of a nearby highway and shot a 36-year-old police officer in the head. The officer was transported to a hospital, where he is listed in critical condition. Police have not determined whether the two incidents are related. The Federal University of Paraiba, some schools and hospitals suspended operations as a precaution to "ensure the safety of clients and professionals," the Joao Pessoa Mayor's Office said. Security has been bolstered in the city while officers try to capture the prisoners who are still at large.