7 people were killed in a prison riot as officers attempted to transfer two dangerous prisoners in Mexico

Seven inmates were killed in a prison riot in southern Mexico, when inmates who resisted transfer to other prisons clashed with police with guns and knives, authorities said late Thursday.

Four police officers and six other prisoners were injured in the riots in the city of Villahermosa, the capital of the Gulf state of Tabasco.

State Police Chief Victor Hugo Chavez he said late Thursday That officers were met by gunfire early in the day when they entered the prison to transfer two dangerous inmates to a federal prison.

One inmate carried a handgun that held up for about three hours, and was protected by 20 fellow inmates, officials said.

Chavez did not specify whether police opened fire on the group, but said: “The authorities must act to defend their lives as well.”

Fires also broke out in the prison during the riots, and crowds of angry and desperate relatives gathered outside the prison, demanding information about family members detained inside.

After regaining control of the facility several hours later, authorities found an assault rifle, five pistols, a hand grenade, 23 machetes, 14 knives, and 23 homemade knives.

They did not explain how the firearms got into the prison. Prisons in Mexico are notorious for loose controls and corruption, to the point where gangs in some prisons take over their own cells and blackmail other prisoners for protection money.

Last year, there was an attack on a government prison in Ciudad Juarez, across the border from El Paso, Texas 17 people were killedIncluding 10 guards. 25 prisoners escaped in the attack, which authorities say was aimed at freeing a local gang leader.

In 2016, A A prison riot resulted in 49 inmates being stabbed, beaten or burned to death In Topo Chico prison in Mexico.