Unknown gunmen have shot at least seven people dead in Burundi’s capital, Bujumbura, ahead of a deadline for civilians to hand over weapons, amid ongoing tensions over President Pierre Nkurunziza’s new term in office.

The armed men forced the victims to lie on the ground in the capital’s southern Kanyosha district before opening fire on them late on Saturday, officials said.

“It was an execution... they killed seven and wounded two,” said Freddy Mbonimpa, Bujumbura’s mayor, adding that a probe had been launched to identify the “assassins.”

The killings came hours before a midnight deadline on Saturday for civilians to surrender their arms.

Following the expiration of the deadline, hundreds of people in Bujumbura fled their homes over fears of fresh violence in the city, leaving key districts almost empty.

“They are virtually emptied of all their inhabitants who have fled because of fear from unfounded rumors of violence,” Mbonimpa said.

Burundi plunged into turmoil back in April, when Nkurunziza announced his bid to compete for a third presidential term. The decision was denounced by the opposition, arguing that the move was contrary to the constitution, which only allows two successive presidential terms.

Many demonstrations against Nkurunziza were held following his announcement to run for a third term. The situation also escalated after the controversial presidential elections in July retained the president in power.

Some 200 people have been killed since the outbreak of violence in April.

The United Nations High Commissioner for Human Rights Zeid Ra’ad Zeid Al Hussein cautioned in September that the country risks sliding back into civil war.

Fought along ethnic lines, a civil war killed around 300,000 people in Burundi between 1993 and 2005.