NAIROBI — Opposition protests in the Somali capital, Mogadishu, were interrupted by gunfire on Friday, heightening a political standoff caused by the government’s refusal to hold elections that were scheduled for two weeks ago.

Videos posted on social media and shared by local news outlets showed opposition leaders marching through the streets of the city before ducking and running for cover as gunfire is heard.

The unfolding chaos in the capital is a flash point in a deteriorating political situation in Somalia, and it risks exacerbating clan-based grievances, emboldening the extremist group al-Shabab and undermining progress the country has made in recent years.

The country has been in crisis after delays to a national and presidential election. The four-year term of Somalia’s president, Mohamed Abdullahi Mohamed, formally ended last week, but he has refused to leave office, setting off a political crisis.

The government put the country under a lockdown before the demonstrations on Friday, suspending all public gatherings. While it said it imposed the restrictions because of the coronavirus pandemic, opposition critics attributed the move to an effort to tamp down protests.

Hassan Ali Khaire, the former prime minister and a prominent opposition figure, said in a post on Facebook that he and several other presidential candidates, lawmakers, other officials and civilians survived an “assassination attempt” at the protest. Mr. Khaire later said in a news conference that shells fired against opposition protesters had landed inside the city’s international airport.

The chaos came just hours after an intense exchange of gunfire erupted in Mogadishu in the early hours of Friday morning. In a statement, Hassan Hundubey Jimale, the Somali minister of internal security, said “armed militias” had attacked military posts with the intention of taking over government buildings. Government forces repulsed the attackers, he said.

Those raids were followed by reports of attacks by the government on other political figures, including Mr. Mohamed’s two presidential predecessors, Hassan Sheikh Mohamud and Sharif Sheikh Ahmed, who said on Twitter that the hotel where they were staying had been targeted.

“The government forces tonight attacked the Ma’ida hotel where I and the former president were staying,” Mr. Mohamud wrote in a post on Twitter. “It is unfortunate that the outgoing president is shedding the blood of citizens who are preparing for a peaceful demonstration to express their views.”

Mr. Ahmed wrote that he believed the attack was ordered by Mr. Mohamed, who is “trying to suppress and force the Somali people from expressing their views peacefully.” The two men had been staying in the hotel along with other opposition figures ahead of Friday’s rally.

Somalia’s president is elected by the country’s lawmakers, a process that was scheduled to take place on Feb. 8, but the country has failed to hold the national elections to select those lawmakers.

The impasse has inflamed tensions among the federal and regional governments and opposition parties. It has also alarmed the international community, with the United Nations, the United States, the European Union and several African countries, urging the parties involved to resolve the electoral issues “in order for credible and inclusive elections to proceed.”

In addition to intensifying attacks from the Qaeda-linked group Shabab, Somalia is battling rising cases of the coronavirus, desert locusts that are destroying crops and climate shocks — creating a humanitarian crisis affecting millions of people. Somalia also severed diplomatic relations with Kenya in December after accusing it of meddling in its internal affairs.

The U.S. Embassy in Somalia also called for “an end to all violence” and urged all parties to finalize an agreement on how to move ahead with the election.

On Friday, the United Nations Assistance Mission in Somalia said in a statement that it was “deeply concerned by armed clashes” in Mogadishu on Thursday night and Friday morning and called for “calm and restraint by all parties involved.”

The clashes, it said, “underscore the urgent need” for government leaders to come together to reach political agreement on the electoral process.

Murithi Mutiga, the Horn of Africa project director for the International Crisis Group, said that despite the unfolding events in the streets of Mogadishu, it was not too late for Mr. Mohamed to build consensus around the election and stave off another crisis in the region.

“The region can hardly afford another crisis,” Mr. Mutiga said. “At a time when Ethiopia is experiencing internal turmoil and its troops are facing off with Sudanese forces over a disputed borderland and with Al Shabab seemingly resurgent in Somalia and northern Kenya, renewed violence in Somalia and the possible fracturing of the security forces along clan lines would be significantly destabilizing.”

Abdi Latif Dahir reported from Nairobi, and Megan Specia from London.