QUITO, Ecuador—Ecuador’s president has declared a state of emergency in the prison system following a battle among gang members in a coastal lockup that killed at least 118 people and injured 79 in what authorities say was the worst prison bloodbath ever in the country. Officials said at least five of the dead were found to have been beheaded. Dozens of police and military vehicles, as well as ambulances, entered the prison compound on Thursday. Helicopters flew over the area. There could be more bodies or seriously injured people in the prison, said Col. Tannya Varela, the national police commander. Hundreds of people gathered outside the crime lab in Guayaquil, hoping to collect the bodies of relatives they believed were killed in the prison. The prosecutors’ office said on Twitter that police were working to identify bodies. Henry Coral, a police official, asked family members to help speed the identification …