Brazilian soldiers were deployed Wednesday to defend government buildings in the capital Brasilia after protesters demanding the exit of President Michel Temer smashed their way into ministries and fought with riot police.

"At this moment, federal troops are already here in (the foreign ministry," Defense Minister Raul Jungmann said in a brief televised statement. "And next there are troops arriving to secure all the ministerial buildings."

Jungmann said the army was ordered out by Temer, who is fighting for his political life after being placed under a corruption investigation.

Violence erupted soon after the crowd, estimated by police at 35,000, marched toward the presidential palace, which is flanked by Congress and government buildings.

While most of the protesters were peaceful, small groups wearing masks threw stones at officers ringing the area and smashed their way into the agriculture ministry and reportedly also the culture and planning ministries. Riot police crouching behind black shields lobbed tear gas and stun grenades into the crowd, sparking running battles.

When protesters set a fire in the agriculture ministry, employees were forced to flee.

"There was an invasion of the ministry's private entrance. They lit a fire in a room, broke photos in a gallery of ex-ministers and confronted police," a spokesman for the ministry told AFP. "The building was evacuated."

Jungmann said the protest had been "peaceful but descended into violence, vandalism, disrespect, attacks on state property, and threats against people."

He said government employees "were terrorized."

There were reports of several injuries and the Brasilia police said that at least one person had been injured by a gunshot.

- Battle over Temer -

Organized by leftist groups and trade unions, the protesters want the resignation of Temer a week after he was placed under a corruption probe.

They also want the end to austerity reforms centered on cuts in the country's generous but unaffordable pension system.

The left smells blood just over a year since Temer took over from Workers' Party president Dilma Rousseff after she was impeached for illegally manipulating government accounts. Opponents say Temer could soon be forced to resign or subjected to an impeachment trial.

"It's the end of this putchist government. That's why the people have taken to the streets," said Francisca Gomes, 59, who came from Sao Paulo for the protest and carried a funeral ribbon carrying the image of the president and the words: "RIP Temer."

Inside Congress, Workers' Party Senator Gleisi Hoffmann echoed those words, saying: "Temer will fall. Everyone says this is government is dead."

- Economic reforms -

Temer says the austerity reforms are already working and that more measures, especially pension reform, are needed.

Latin America's biggest economy has been stuck in deep recession for two years and is just now showing the first signs of returning to growth, although unemployment is at nearly 14 percent.

However, Temer has been on the ropes since allegations that he attempted to pay hush money to a jailed politician and was involved in bribery. The scandal follows a landslide of other corruption allegations against much of Temer's government and Congress in a huge probe known as "Operation Car Wash."

For now, the president is trying to shore up his congressional alliance to resist calls for his impeachment. He has said he did nothing wrong and will not resign.

But analysts say that intense negotiations are going on behind the scenes to find the least traumatic way possible for Temer to be eased out.

Because he has no vice president, the constitution would require a 30-day period led by the speaker of the lower house, followed by an indirect election in which Congress picks a new president to rule until after scheduled elections in October 2018.