There is a heavy military presence in Guinea Bissau's capital after reports that factions within the military opened fire, prompting the prime minister to seek refuge in a foreign embassy.

Witnesses say armed troops from different military units were patrolling the streets of Bissau, including near the home of Prime Minister Carlos Gomes.

Diplomats said Mr. Gomes went to a nearby embassy, but has since returned to his home.

Witnesses say some soldiers also attacked the armed forces headquarters in Bissau.

It was not immediately clear why the troops fired weapons in this West African country, which has a history of instability and coup attempts.

Some reports suggest the troops were publicly protesting for a pay raise, while others suggest that incident stems from a rivalry between the Army chief, General Antonio Indjai, and the head of the Navy, Rear-Admiral Bubo Na Tchuto.

President Malam Bacai Sanha has been in a Paris for several weeks, after undergoing a medical procedure for an undisclosed condition. The president is known to have diabetes and trouble with the hemoglobin levels in his blood.

Mr. Sanha was elected president of this former Portuguese colony in 2009, four months after the assassination of President Joao Bernardo Vieira.