"An unknown number of people died as they tried to flee Amarula hotel", Human Rights Watch regional director Dewa Mavhinga told AFP. The fate of most of the other foreign workers is still unclear.
The commission said that some of these nationals were already back home while others had been moved to safe areas within Mozambique. Up to 10,000 others were awaiting evacuation, according to aid agencies.
An unknown number of militants began attacking the town, a gas hub in the province of Cabo Delgado, on Wednesday, forcing almost 200 workers, including foreign employees, to evacuate a hotel where they had taken refuge.
Islamist militants have seized control of the northern Mozambique town of Palma, near a huge gas project involving French oil major Total and other worldwide energy companies, security sources said on 27 March 2021.
Attacks on the site in January prompted the firm to suspend work to extract gas from offshore.
In the last three days, government security forces had prioritised "the rescue of hundreds of citizens, nationals and foreigners", said Saranga, without giving a breakdown of the numbers.
Families have gathered at the airport in Pemba waiting for news of relatives but most communications with Palma and the surrounding area have been cut off by the insurgents. "And they were telling us that they were running for safety", Zenaida Machado, the Human Rights Watch representative in Mozambique, told the Associated Press.
Jihadist militants staged the surprise raid, sending terrified residents into nearby forests, while gas and government workers sought shelter at the hotel.
The U.K.'s The Times newspaper says a British contractor was also among those killed in the convoy ambush.
The beach remained under insurgent fire, preventing rescue efforts from air or sea, according to the reports.
Thousands of escapees arrived on boats in Pemba, the provincial capital around 250 kilometres to the south, according to sources there.
The fresh rebel violence brings into question the fate of Total's gas project, one of Africa's biggest private investments.
The Cabo Delgado liquefied natural gas project has been a recurring concern due to the fragile security situation in the region. It said none of its staff at the Afungi site were victims of the attack.
"We are deeply concerned by the still evolving situation in Palma where armed attacks began on March 24, reportedly killing dozens of people", United Nations spokesman Stephane Dujarric said.
The company had just announced it would restart work after receiving security guarantees from the government when last week's attack occurred, forcing it to reconsider once again.
Islamist rebels affiliated with IS have been carrying out attacks in northern Mozambique since 2017. However, the attackers are widely believed to be from a group that locals refer to as al-Shabab, although the insurgents don't appear to have any direct link to the Somalia group of the same name. The rebels have been active in Cabo Delgado province since 2017 but their attacks became much more frequent and deadly in the past year.