An explosion that killed five Canadian tourists and two workers on Sunday at a hotel on Mexico's Caribbean coast was caused by a build-up of gas from a nearby swamp, authorities have said.
Among the dead to have been identified are a man who was married days earlier and a father and his nine-year-old son.
The blast in Playa del Carmen hurled the floor of the building through the ceiling and blew out windows, said the attorney general of Quintana Roo state.
Nine people remain in hospital.
Initial investigations into the blast at the Grand Riviera Princess hotel suggest gas that exploded beneath the building was from a nearby swamp, state prosecutor Francisco Alor said.
"The report suggests an accumulation of gases produced by decomposing organic material in the subsoil, and this gas produced the explosion," Mr Alor said.
The 676-room resort sits on a concrete platform on a swampy area near the beach - located in a region known as the Maya Riviera, about 90km (55 miles) from Cancun.
A statement from Canada's Foreign Affairs and International Trade department confirmed the death of one of the Canadians and said that officials had received unconfirmed reports that three Canadian citizens were missing and seven were injured.
Those who remain in hospital following the explosion include four Canadians, three Mexican employees of the hotel and two Americans, Mr Alor said.
A large number of Canadians, including some attending a wedding and others on a company holiday, were staying in the luxury hotel at the time of the blast.
James Gaade, an Ontario resident and guest staying at the hotel, told the Associated Press news agency he estimated roughly 50-70% of those staying at the resort were Canadian.
"Everyone said their hotel room shook. The glass at neighbouring restaurants all cracked and blew out. The tiki hut that was in the area, that was on fire," Mr Gaade said.
The blast, which left a crater in the ground about 1m (3.3ft) deep, occurred in one of the resort's many buildings.