Over one thousand prisoners escaped four Brazilian prisons on Monday, when their day-release privileges were reversed and limitations were placed on visitors amid concerns about the coronavirus pandemic.

The inmates escaped the night before their privileges were set to be revoked, Newsweek reports. Footage surfaced online of reportedly 400 prisoners fleeing from Mongaguá penitentiary in Sao Paulo, while other clips show the riot police trying to take back control of one prison.

In a statement released on Monday, the Sao Paulo state prison authority said that 174 inmates had been recaptured but conceded that it was “still tallying the exact number of fugitives” that had fled the semi-open jails in Tremembé, Porto Feliz, Mirandópolis, and Mongaguá. Brazilian media believes over 1,500 prisoners escaped.

The Easter prison break is one of five annual breaks for prisoners in semi-open facilities who work during the day. Brazilian officials chose to cancel the temporary releases so that the 34,000 prisoners who went into the public wouldn’t bring the virus back to the prison, where the population is vulnerable to infectious diseases. Trials and other court activities have also been suspended due to coronavirus.

“The measure was necessary because the benefit would include more than 34,000 convicts of the semi-open regime who, returning to prison, would have high potential to install and spread the coronavirus in a vulnerable population, generating health risks to servers and custodians,” the prison department said.

Later, it added that riot police “taking care of the situation” had regained command at all four prisons, which aren’t supervised by armed guards due to the semi-open program. Prison officers who had been taken hostage were also released. Prison riots in Sao Paulo are not unusual.

Brazil reported 234 confirmed cases of the virus, as of Tuesday. Brazilian President Jair Bolsonaro tested positive for the virus but immediately denied that he was sick. He took another test and it came back negative. Bolsonaro and at least two of his associates had come into contact with Donald Trump earlier this month. Trump later tested negative.

American federal prison officials have banned family, friends, and attorneys from seeing inmates for at least the next 30 days due to the virus.