At least one American has been safely evacuated from Mozambique following deadly attacks by ISIS-linked rebels who left beheaded bodies strewn on beaches and streets, according to a senior official with the U.S. Department of State.

John Godfrey, the State Department’s acting special envoy for the global coalition to defeat ISIS, condemned the “sheer brutality” of the attacks in the coastal northeastern town of Palma and said the local jihadist group responsible has become increasingly brazen.

“The situation there is still unfolding but the U.S. government is closely monitoring events on the ground, and the attacks there are horrific, frankly, and show a complete disregard for the life, welfare and security of the local population,” Godfrey said during a press briefing Monday afternoon. “We were aware of one American citizen who was on the ground in Palma and that individual, as we understand it, has successfully been evacuated.”

ISIS, officially known as the Islamic State, claimed responsibility Monday for the attacks in Palma in Mozambique’s natural gas-rich Cabo Delgado province, saying the offensive was carried out by fighters from its Central African Province division, which also has a presence in the Democratic Republic of the Congo, according to SITE Intelligence Group, a company that tracks extremist groups. ISIS alleged its insurgents had seized the “strategic city” in the southern African nation, taking control of buildings, factories, government offices and banks, and killing more than 55 people there, including Mozambican soldiers, Christians and foreign nationals.

“Attacks such as these are clear indicators that ISIS continues to actively seek to spread its malign activity to new fronts,” Godfrey told reporters Monday. “Ensuring the enduring global defeat of ISIS will entail effectively countering ISIS branches and networks outside of Iraq and Syria, and we as a coalition recognize that.”

On March 10, the U.S. government designated the group in Mozambique as a foreign terrorist organization, issuing sanctions and making it a criminal offense to provide material support to them. The State Department said the group, referred to as ISIS-Mozambique, had pledged allegiance to the Islamic State and was acknowledged as an affiliate in August 2019. But the group, known locally as Ahlu Sunnah Wa-Jama, has been waging its own Islamist insurgency in northern Mozambique since 2017, according to Chatham House, a London-based independent policy institute.

The port of Mocimboa da Praia, located in Cabo Delgado province about 50 miles south of Palma, was briefly occupied during attacks claimed by the group in 2017, according to Chatham House. Last year, the group orchestrated “a series of large-scale and sophisticated attacks resulting in the capture of the strategic port” once again, the State Department said. The Mozambican government has yet to regain control of Mocimboa da Praia, and the violence has led to the displacement of nearly 670,000 people within northern Mozambique.

The attacks on Palma began March 24, when rebels raided the town from three different directions and killed dozens of people, according to Col. Omar Saranga, spokesman for the Mozambican Ministry of Defense.

“The defense and security forces are pursuing the enemy’s movement and are working tirelessly to restore security and order as quickly as possible,” Saranga said in a statement on March 25.

A number of people, including foreign nationals, reportedly sought refuge in a local hotel as the rebels clashed with security forces. When some of them finally tried to flee over the weekend, the rebels ambushed their convoy and killed seven people, according to Saranga.

More than 1,300 people fleeing the violence have arrived by boat in the port city of Pemba, but “hundreds” remain unaccounted for in Palma, according to Human Rights Watch, a New York-based non-governmental organization that investigates and reports on abuses happening around the world.

“Media reports and witnesses said bodies, some of them beheaded, were lying on the streets and beaches of Palma,” Zenaida Machado, researcher for Human Rights Watch’s Africa Division, wrote in a dispatch Monday. “Phone lines to Palma have been down, making it hard to obtain information.”

A State Department spokesperson told ABC News that the “U.S. Embassy in Mozambique is in touch with Mozambican authorities, international missions, and the private sector regarding the ongoing situation and humanitarian relief efforts.”

Palma is situated next to liquefied natural gas projects reported to be worth billions of dollars with investments from Total, Exxon Mobil and other companies.

A Total spokesperson told ABC News that there are no casualties among personnel in the region and that the company has reduced staff at its nearby Afungi site to an absolute minimum in response to the Palma attacks. Meanwhile, an Exxon Mobil spokesperson told ABC News that the company continues “to monitor security developments in the region.”

ABC News’ Ibtissem Guenfoud, Cindy Smith and Christine Theodorou contributed to this report.