At least six people were killed as Indonesia's capital erupted in violence when police clashed with protesters opposed to the re-election of President Joko Widodo.
Police sirens blared as fresh skirmishes broke out Wednesday evening with thousands of protesters chanting and waving Indonesian flags in the heart of the capital.
Some hurled stones and fireworks at riot police who lined up behind a razor wire barricade near the election supervisory agency building.
Police pushed back the main group of rioters after firing tear gas and rubber bullets at the demonstrators.
At least three officers were injured in the clashes and carried away, an AFP reporter on the scene said.
Earlier, dozens were arrested and parts of Jakarta were littered with debris and burned-out cars, as the violence triggered security advisories from the US and Australian embassies.
Authorities also restricted access to some social media in a bid to stop rumours and fake news from spreading online.
National police chief Tito Karnavian said six people had died, but denied authorities had fired live rounds at protesters, and called for calm.
"Some had gunshot wounds, some had blunt force wounds but we still need to clarify this," he told reporters.
Jakarta's governor Anies Baswedan said about 200 people had been injured.
The violence came after Indonesia's election commission on Tuesday confirmed Widodo had beaten retired military general Prabowo Subianto for the presidency in a poll held on April 17.
Subianto has said he would challenge the results in court -- as he did, unsuccessfully, against Widodo in 2014 -- but also warned his claims of widespread cheating could spark street protests.
That was borne out early Wednesday as protesters set market stalls and cars on fire while hurling fireworks and rocks at security personnel clad in riot gear and holding shields, an AFP reporter said.
Authorities blamed the violence on paid "provocateurs", citing money-filled envelopes they said were found on some of the 257 demonstrators arrested.
The early morning clashes started after several thousand Subianto supporters rallied peacefully on Tuesday evening.
- 'Don't want chaos' -
On Wednesday, roads were blocked off in parts of the sprawling metropolis -- with some shopping malls, businesses and schools also closed as small groups of protesters engaged in skirmishes with police.
"I open myself to anyone who wants to develop this nation, but I won't tolerate anyone who tries to disrupt public security, the democratic process or the unity of our... country," Widodo said at a press briefing, flanked by his chief security minister and the head of the military.
Early Thursday, Subianto called for the protesters to go home, and again urged them to avoid violence.
"Trust in your leaders. We are struggling in the legal and constitutional way," he said in a video on his Twitter feed.
"We're all looking for the best solution for the nation."
The former military man -- who has strong ties to the Suharto dictatorship that collapsed in 1998 -- has kept up a steady stream of rhetoric since unofficial results for last month's poll put bitter rival Widodo ahead by a wide margin.
The soft-spoken Widodo -- who pointed to his efforts to boost Southeast Asia's biggest economy with a huge infrastructure push -- stood in stark contrast to Subianto, a fiery strongman who courted Islamic hardliners and promised to boost military and defence spending.
Election officials and analysts have discounted Subianto's claims, but many supporters appeared convinced of rampant cheating in the world's third-biggest democracy behind India and the United States.
"We came here to demand justice because there was fraud in this presidential election," protester Mato told AFP.
"We don't want chaos, but that depends on the police," he added.
More than 30,000 troops had been deployed across the city in anticipation of unrest, and the elections commission office was barricaded with razor wire and protected by scores of security personnel.
Elsewhere, hundreds took part in a peaceful rally over election cheating claims in Sumatra's Medan city, while a police station was torched in Pontianak on Borneo island.
The protests in support of Subianto sparked a backlash online from opponents with the hashtag #TangkapPRABOWO (#ArrestPrabowo) trending widely on social media.
Tensions have also spiked since police said last week that they had arrested dozens of Islamic State-linked terrorism suspects who had planned to cause chaos by bombing protests.