Tunisia refuted claims on Tuesday that a boat from a flotilla heading to Gaza was struck by a drone off its shores, explaining that the blast originated from within the vessel itself.

The Global Sumud Flotilla, an independent aid organization, reported on Monday that a primary boat on its journey to the Gaza Strip was supposedly hit by a drone in Tunisian waters.

The explosion resulted in fire damage to the Portuguese-flagged vessel’s top deck and storage areas below deck, but according to a GSF statement, all six passengers and crew members escaped harm.

“Efforts to intimidate and disrupt our mission won’t deter us,” the organization stated. “Our non-violent mission to breach the siege on Gaza and support its residents remains unwavering and resolute.”

According to GSF, an investigation is ongoing. Comprising about 20 boats and participants from 44 nations, including activist Greta Thunberg, this marks the most extensive civilian maritime effort to challenge the Israeli blockade of the Palestinian area.

Meanwhile, Tunisian authorities dismissed the assertion, claiming the blast was internal, as reported by Reuters. A spokesperson for the National Guard told local outlets that the claims of a drone strike on the flotilla “are unfounded.”

Miguel Duarte, a crew member, said the suspected drone stopped close to the flotilla, moved slowly to the front, and then dropped “what was obviously a bomb” on the forward part of the deck.

“Let me be clear 100%. It was a drone dropping a bomb on the forward deck of our ship,” Duarte said when asked whether the team was “absolutely certain that this was a drone attack,” a video he posted on Instagram shows.

“I’m OK, but we could have been killed, right?” Duarte said, citing the deaths during the Israel-Hamas war of humanitarian and medical workers.

“We know the dangers that we’re facing,” he said.

After the explosion, crew members repeatedly yelled for help and sounded the fire alarm, according to a CCTV video shared by Francesca Albanese, the U.N. special rapporteur for the West Bank and Gaza.

“If it’s confirmed that this is a drone attack, it will be an assault and aggression against Tunisia and against Tunisian sovereignty,” Albanese said after the incident. “And again, we cannot keep on tolerating this and normalizing the illegal.”

Demonstrators gathered at the port of Tunis around 2 a.m. local time (10 p.m. Monday ET), with some waving Palestinian and Turkish flags and chanting “Free Palestine,” according to a video reposted by GSF.

Starvation deaths in Gaza surged after Israel’s blockade in March, and aid was resumed in May under a system backed by the U.S. and Israel. Since then, nearly 1,400 people have died and 4,000 more have been injured while seeking food, with at least 859 killed near aid sites, the United Nations says.