Federal police are investigating an apparent hacker attack on the website of Brazil’s president, just a day after President Dilma Rousseff took office, officials told media Tuesday.

The attack on Sunday was being investigated by the Federal Data Processing Service, according to official sources cited by G1 reports and Agencia Folha.

“The federal police will probe anybody responsible for attempts to block the security of the president’s office,” Serpro’s spokesperson Carlos Marcos Torres told G1.

A group calling itself the “Fatal Error Crew” took credit for the apparent attack in a Twitter posting.

Serpro said there was an intentional flood of attempts to access presidencia.gov and brasil.gov, which knocked the sites out of service for a few hours.

In April, the ruling Workers Party had its website knocked out by a hacker for 24 hours.