A violent prison riot in the Ecuadorian coastal city of Guayaquil has left at least 100 people dead and 52 injured, prompting military troops to cordon off the compound on Wednesday.

At least six people were beheaded, the national prosecutor's office said.

The clashes took place on Tuesday between armed inmates aligned to rival gangs, known as the "Los Lobos'' and "Los Choneros'' prison gangs, officials said, adding that the riot involved gunfire, knives and explosions.

Bolivar Garzon, who leads SNAI — a national service that provides support to those in conflict with the law — said he did not want to report an official death toll after visiting the site.

"I think we are going to reach 100 dead, I don't want to give an official figure," local news agency NotiMundo cited him as saying. 

But the office later wrote in a tweet that over 100 people were killed and 52 injured.

Television images showed inmates firing from the windows of the jail, and the detonation of firearms and explosives.

"Thanks to police entering [the prison], more deaths inside were prevented," said Fausto Buenano, the police chief of Guayaquil city. He said police were attacked with guns.

Police Commander Fabian Bustos told reporters that the police and military operation had regained control of the jail after five hours. He added that several weapons had been seized.

President declares state of emergency

Ecuador's prison system has become a battleground with clashes typically breaking out between prisoners tied to Mexican drug gangs such as the Sinaloa and Jalisco New Generation cartels.

Guayaquil is a major hub for shipping South American cocaine north, particularly to the United States.

More than 120 inmates have been killed in prison clashes so far this year.

Earlier this month, Guayaquil's Prison Number 4 was attacked by drones as part of "a war between international cartels," prison authorities said. There were no casualties in the attack.

In February, riots in at least three jails including Guayaquil left 79 inmates dead, several of them beheaded.

Violent rioting prompted President Guillermo Lasso to decree a state of emergency in the country's prison system in July.

Ecuador's prison system has around 60 facilities designed for 29,000 inmates, but jails  are overburdened with overcrowding and staffing shortages.

mvb/sms (EFE, AFP, AP)