MEXICO CITY - At least 16 prisoners were killed, five others wounded after riots occurred Tuesday afternoon in a prison in the northern Mexican state of Zacatecas, local authorities said Wednesday.

A conflict between different groups of prisoners broke out at 2:30 pm local time (2030 GMT) at the Regional Center for Social Reintegration in the town of Cieneguillas, about 13 km away from Zacatecas City, the state capital, Ismael Camberos, public security secretary of the Zacatecas state, said at a press conference Wednesday evening.

Local police soon intervened and managed to put the situation under control in the afternoon, Camberos said.

The police arrested one prisoner with a firearm, and found three more guns and various knives in the prison, he said.

Among the 16 fatalities, 15 died at the prison and one died later at hospital. The five wounded are in stable condition, he said.

Officials believe that the guns could have been brought inside the prison during visiting hours on New Year's Eve, because no such weapons were found during an inspection at the weekend, Camberos said earlier on Wednesday during an interview with Mexican radio program Aristegui en Vivo.

"We are waiting for the results of the investigation --this includes the director, senior managers and commanders -- to determine if we are going to remove staff," he said, adding that local authorities have investigated 60 prison guards.

The prison in Cieneguillas was built some 30 years ago, when Mexico had a different security landscape, he said.

"We are investing and we are trying to modernize this prison," he added.