NAIROBI (Reuters) - The U.S. embassy in Eritrea said it has received reports of gunfire in several parts of the capital, Asmara, after protests erupted in one of Africa’s most secretive nations.

“The embassy advises U.S. citizens to avoid the downtown area where protests appear to be more prevalent,” it said in a statement late on Tuesday.

“Avoid areas where demonstrations are taking place and exercise caution when in the vicinity of any large gatherings, protests, or demonstrations.”

It was not immediately clear what had caused the protests.

Opposition outlets said the incidents were triggered after the government tried to close down an Islamic school in a predominantly Muslim district.

In some footage posted online, shots are heard being fired to disperse crowds.

Via Twitter, Information Minister Yemane Ghebremeskel downplayed the protests, saying: “Small demonstration by one school in Asmara dispersed without any casualty.”

Eritrea, which sits on the Red Sea coast next to one of the world’s busiest shipping lanes, seceded from Ethiopia in 1991 after a three-decade war for independence.

Conflict broke out once again seven years later over a border spat with neighboring Ethiopia, and the UN has since accused the government in Asmara of committing crimes against humanity under the guise of national security.

A U.N. Commission of Inquiry report last year said that atrocities - including an indefinite military national service program that amounted to mass enslavement - had been committed since the country’s independence and were ongoing.

Eritrea denies the charges.