Five friends from Argentina were among those killed in a truck attack in New York on Tuesday.
Eight people were killed and 11 injured when the driver of the truck hit people on a cycle path in Lower Manhattan.
A 29-year-old man, an Uzbek immigrant, was shot and injured by police as he left the vehicle. He is under arrest.
New York Governor Andrew Cuomo told CBS that a note was found inside the truck referring to the Islamic State militant group (IS).
The suspect, named by media as Sayfullo Saipov, reportedly shouted "Allahu Akbar" ("God is greatest") as he left the truck. Mr Cuomo said he was radicalised in the US.
It is the deadliest terror attack in the city since 11 September, 2001.
The deaths of five Argentines were confirmed by the country's foreign ministry. They were part of a group of nine friends in New York to celebrate the 30th anniversary of their graduation from a polytechnic college in the central city of Rosario, Argentine media said.
One of the men who died, steel firm owner Ariel Erlij, helped pay for the friends' trip, La Nación newspaper reported (in Spanish).
The men - all aged 48 or 49 - were named as Hernán Diego Mendoza, Diego Enrique Angelini, Alejandro Damián Pagnucco, Ariel Erlij and Hernán Ferrucci.
Another of the friends, Martín Ludovico Marro, is being treated in hospital. Three days of mourning have been declared in Rosario.
Belgian media said a 31-year-old mother-of-two from Staden in Flanders was also killed, but has not been publicly named at her husband's request. Three other Belgians were wounded.
Two other victims have not yet been identified.
Who is the suspect?
The NYPD said only that the attacker was a 29-year-old man.
US media named him as Sayfullo Saipov, who had reportedly lived in Tampa, Florida, and Paterson, New Jersey.
He arrived in America from Uzbekistan in 2010 and is believed to be a legal resident in the country. Car-share service Uber confirmed he had been working for them.
hree officials said Mr Saipov had previously come to the federal authorities' attention because of an unrelated investigation, the New York Times reported.
Police records show he was arrested in Missouri last year over a traffic fine.
Uzbekistan's president, Shavkat Mirziyoyev, told Donald Trump his country was ready to "use all forces and resources" to help investigate the attack. Uzbek officials have not yet confirmed the identity or nationality of the attacker.
What has been the reaction?
President Trump took to Twitter to call the attacker "a very sick and deranged person", adding: "We must not allow ISIS [Islamic State] to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!"
He also announced he had ordered extreme vetting to be stepped up, without elaborating further.
Mr Trump first said he wanted "extreme vetting" of immigrants during his presidential campaign last August. As president, he introduced a ban on arrivals to the US from a number of mainly-Muslim countries - a move that has been challenged legally and is due before the Supreme Court in the coming weeks.
The American Civil Liberties Union civil rights group said the term extreme vetting was a "euphemism for discriminating against Muslims".
Early on Monday, he called for a "merit-based" visa system and attacked Democrat rival Chuck Schumer for having pushed for the creation of a diversity visa - or green card lottery - in the early 1990s.
A diversity visa is given to residents of countries with few immigrants to the US. A friend of Mr Saipov told the BBC the 29-year-old had obtained his residency this way.
New York City Mayor Bill de Blasio said the incident was a "cowardly act of terror aimed at innocent civilians".
"We know that this action was intended to break our spirit. But we also know that New Yorkers are strong, New Yorkers are resilient and our spirit will never be moved by an act of violence and an act meant to intimidate us," he said.