Venezuelan opposition leader Juan Guaido said on Monday that unidentified armed men had “threatened” him with arrest at his apartment building, and an opposition spokesman said a close Guaido ally had been arrested.

Since 2019, Guaido has been recognized by dozens of countries, including the United States, as Venezuela’s legitimate head of state on the basis that socialist President Nicolas Maduro rigged his 2018 re-election. Maduro, who retains the support of the military and denies that the election was rigged, has labeled Guaido a U.S. puppet and has accused him of conspiring to oust him in a coup.

Guaido’s wife, Fabiana Rosales, said on Twitter on Monday afternoon that security forces had entered their apartment building in an attempt to detain Guaido.

When reporters arrived outside Guaido’s residence in eastern Caracas some minutes after Rosales’ tweet, neighbors were protesting. Some gathered around two white, unmarked trucks in which sat men bearing bulletproof vests and assault rifles, some in balaclavas, according to a Reuters witness. Others wore hats that said DIE – the Spanish acronym for the Directorate of Intelligence and Strategy police unit.

“Dictatorship!” some of the neighbors yelled at the men. Others leaned out nearby windows banging on pots and pans.

Shortly afterwards, an unmarked gray Toyota truck filled with police raced out of the garage in the basement, leaving the residential complex. Minutes later, Guaido emerged from an SUV.

Guaido told the reporters gathered outside the building that the men had left, and said it was unclear which branch of the security forces they had belonged to.

“They intercepted us and pointed their weapons at us, in the basement,” Guaido told reporters. He said he had been leaving his building together with a driver to assist his close ally, fellow opposition politician Freddy Guevara, who minutes earlier had been arrested on a Caracas highway.

A spokesperson for Guaido’s office said Guevara, who was pardoned less than a year ago on 2017 charges of instigating violence, was taken to the Helicoide prison in Caracas. The reason for his arrest was unclear.

Venezuela’s information ministry did not respond to a request for comment.

Guaido’s office circulated two videos which they said showed the incident in Guaido’s basement. The videos show at least two men with bulletproof vests and balaclavas approaching a car, pointing assault rifles. Guaido is sat in the passenger seat. One of the men opens the driver’s door and forces the driver onto the ground, yelling “Get out!,” the videos show.

The incidents took place as the government and opposition prepare for negotiations aimed at resolving the South American country’s deep political crisis.