Demonstrators in the Republic of Congo protesting their president’s bid for a third term were shot at and tear-gassed by police Tuesday in the capital of Brazzaville, with at least four people reported dead, Reuters reported. A Sunday referendum on the country’s constitution seeks to allow President Denis Sassou Nguesso, who has served two terms since 1997, to serve a third term.

Early reports indicated that others have been wounded as authorities clashed with protesters, the BBC reported. After police opened fire, protesters remained in the streets, some burning tires and putting up barricades. Mobile communications such as texting and Internet services have been cut in Brazzaville amid the turmoil.

Nguesso first ruled the country from 1979 until 1992, when he lost a re-election bid, according to Agence France-Presse. He returned to power in 1997 after a civil war in the country.

"President Sassou Nguesso is organizing a coup d'etat, a constitutional coup d'etat," Paulin Makaya, leader of the opposition United for Congo party, told Reuters. "We call on international nations, the United States and France, to heed what is happening here in Congo Brazzaville."

Republic of Congo authorities banned protests earlier Tuesday, and hours before the ban went into place police attempted to get a crowd of protesters to disperse by firing shots into the air. Shops and schools have closed, and buses and taxis have seemingly not operating as well.

"The radical opposition promised to march on the presidential palace today, so it's logical security forces took steps to preserve the peace of our citizens, freedom of movement, and the stability of the state," government spokesman Thierry Moungalla told Radio France International, which had its broadcast signal cut Tuesday.

Four people were injured Sunday in the Republic of Congo city of Pointe-Noire during a demonstration in which police detained five opposition leaders, according to AFP.