A group of tourists had police protection and permission from Egyptian authorities to stop near an oasis in Egypt's Western Desert before they were attacked by an Apache military helicopter, a relative of one of the victims said.
The claim contradicted initial statements from the Egyptian and Mexican governments, which both said the group of mostly Mexican citizens were in an unauthorized area when they stopped to have a picnic.
In all, 12 people were killed when the convoy was mistaken for a group of militants, officials said, but the full list of victims and their identities have not been released as of Monday afternoon.
Gabriela Bejarano Rangel told VICE News her brother Rafael Rangel, an alternative healer and musician, was one of eight Mexicans killed in the attack. Rafael Rangel was also the tour-guide who led the group to the Farafra oasis, and his mother was also in the group.
"My brother was the guide. He's done this tour for many years," Bejarano said. "Contrary to what the Mexican authorities said, they were being guarded by the local police, and they did have permission to be in the area where they were attacked."
Claudia Ruiz Massieu, Mexico's foreign minister — and most recently, the tourism minister — said on Monday that only two Mexicans were confirmed dead by the government. Ruiz Massieu said Mexico's ambassador in Cairo was at the hospital where six other Mexican nationals were being treated for injuries.
Egyptian security and judicial sources later told Reuters that eight Mexicans and four Egyptians were killed, and that ten people were wounded, eight Mexicans and two Egyptians. Mexico's foreign office later confirmed the eight citizens dead.
Egypt's foreign ministry said that the victims were mistaken for "terrorist elements." Egypt is battling an Islamic State-affiliated insurgency in the area, which was described as "off-limits" in early reports. Tourism authorities in Egypt were already convening a crisis group to follow-up on the incident out of fear it could affect the country's tourism market, said Daily News Egypt.
"It's a very safe tour," Bejarano, the tour-guide's sister, told VICE News, adding that she herself has taken it.
"The company responsible for it is very strict [with security], because they fear losing their permits or being jailed," she added.
Mexican officials told VICE News they could not verify the relative's claims and said the foreign ministry and Egyptian authorities were still investigating what happened. Some of the victims were gunned down as they tried to flee to a sand dune, a witness told The New York Times.
"We trust Egypt's government will act with the political will and speed that this incident merits," Mexico's foreign ministry said on Twitter.
Most of the victims were from the Mexican cities of Guadalajara and Leon, the relative added.
In photo above, Mexican foreign minister Claudia Ruiz Massieu and President Enrique Peña Nieto late Sunday talking to authorities in Egypt.
Daniel Hernandez and Reuters contributed to this report.