Six people, including one US citizen, have been arrested and seven reportedly killed as Haitian security forces pursued the gunmen responsible for the assassination of the Caribbean country’s president, Jovenel Moïse. As Haiti reeled following the first assassination of a serving president in the Americas since John F Kennedy’s 1963 shooting, there were chaotic scenes in the capital, Port-au-Prince, on Thursday. Angry civilians reportedly apprehended two male suspects while police laid siege to two buildings in which other suspected assassins were supposedly holed up. “They killed the president! Give them to us. We’re going to burn them!” the pair’s captors chanted as they delivered the men to police, according to the Associated Press. Footage posted on social media showed two bedraggled men being bundled through the streets of Port-au-Prince by locals, one with his hands bound behind his back with white cords. Members of the throng reportedly torched several bullet-riddled vehicles they believed belonged to the suspects. Haiti’s interim prime minister, Claude Joseph, called on citizens to hand suspects over to police rather than lynch them. “I am calling for calm. Everything is under control. This barbaric act will not remain unpunished,” Joseph claimed on television. Haiti’s police chief, Léon Charles, told local radio seven suspects had been shot dead and six arrested following Moïse’s killing. The masterminds were still being sought. Elections minister Mathias Pierre said 26 people were in the group that killed the president. Helen La Lime, a veteran US diplomat who is the UN’s special envoy for Haiti, told journalists she had been informed that “a larger group of possible perpetrators” had been surrounded by police after taking refuge in two buildings in Port-au-Prince. Speaking after an emergency UN security council meeting in New York, La Lime said Haiti’s prime minister had told her the presidential compound had been invaded by a Spanish- and English-speaking “commando unit”, whose heavily armed members killed the president after posing as “a DEA force”. “I don’t know who this commando is,” La Lime added. Haitian authorities described several of the suspects as “foreigners”, with the Washington Post naming one of the six detained men as James Solages, a US citizen of Haitian descent. Robert Fatton, a Haitian politics professor from the University of Virginia, said well-placed government sources had told him other foreign nationals were involved. “From what I gather they were Haitian-American or American,” Fatton said. Moïse, a 53-year-old former banana exporter who took office in 2017, was murdered at his family home in the hills above Port-au-Prince at about 1am local time on Wednesday. The first lady, Martine Moïse, was also wounded and evacuated to Miami where she is reportedly in a stable condition. According to new details that have emerged in local reports, the attackers tied up staff, and one of Moïse’s three children survived by hiding in her brother’s bedroom. Moïse was shot at least a dozen times and died at the scene, according to Carl Henry Destin, a judicial official, who said the president’s office and bedroom were ransacked. “We found him lying on his back, with blue trousers, a white blood-stained shirt, his mouth open, the left eye gouged out,” said Destin told Haiti’s main newspaper Le Nouvelliste. As details of the audacious raid emerged, Haiti was enveloped by profound political uncertainty and the streets of the capital emptied as many residents chose to stay at home. “I really don’t know what to say … the insecurity is too much,” said Darline Garnier, a 23-year-old university student from Pétionville, near where the president was killed. “It’s a humiliation for our nation,” said Luckner Meronvil, a 46-year-old taxi driver, tears welling in his eyes as he spoke. Theories about who was behind the killing ran wild in Haiti and in the neighbouring Dominican Republic, which shares the same island. Amid claims that some of those involved in the attack had spoken Spanish, the Dominican paper Diario Libre reported that investigators there were examining the possibility that some of the assassins may have used the country to access or flee Haiti. And in the febrile atmosphere, competing – and so far unverified – theories have continued to emerge, one suggesting that a hit squad of Colombians and Venezuelans contracted to powerful figures in Haiti involved in drug trafficking and other criminality had ordered the killing, or that the killing involved individuals linked to Moïse’s own security staff. Many people in Haiti had wanted Moïse to resign. Since taking over in 2017 he had faced calls to leave office and mass protests, first over corruption allegations and his management of the economy, and then over his increasing grip on power. On Thursday Haitians woke up to a country without a head of state, with a parliament long suspended, two rival interim prime ministers – one of whom was due to be sworn in during the coming days – and a constitutional legal vacuum after the death from coronavirus of the head of its supreme court. That has generated confusion about who is the legitimate leader of the country of 11 million people – Joseph, who has assumed power for now, or Ariel Henry, who was appointed as PM by Moïse just before his death and was due to be sworn in this week. “All the cards are up in the air,” Fatton said of the apparent struggle between Henry and Joseph. Ryan Berg, an analyst with the Center for Strategic and International Studies, said: “I can picture a scenario under which there are issues regarding to whom the armed forces and national police are loyal, in the case there are rival claims to being placeholder president of the country.” Pierre, the elections minister, said on Thursday night that a presidential vote as well as a constitutional referendum that had been slated for 26 September before the assassination of Moise would go ahead as planned. “It (the vote) was not for Jovenel Moise as president: it was a requirement to get a more stable country, a more stable political system, so I think we will continue with that,” said Pierre, adding that preparations had long been underway and millions of dollars disbursed to carry out the votes.