The Pearl Continental Hotel in Pakistan’s southwestern port city of Gwadar.

Three gunmen attacked a luxury hotel in Pakistan’s southwestern port city of Gwadar on Saturday, killing at least one guard and battling security forces from inside the building, security officials and the army said.

Balochistan Home Minister Ziaullah Langove said most guests had been evacuated from the five-star Pearl Continental Hotel, which helicopters circled as fighting was underway. He said there were reports of casualties, but did not give details.

The military said three gunmen killed a guard at the entrance to the hotel when they entered. Security forces had cordoned off the area and cornered the attackers in a staircase leading to the top floor, the military said in a statement

Gwadar is a strategic port on the Arabian Sea being developed as part of the $60 billion China Pakistan Economic Corridor, which is itself part of China’s mammoth Belt and Road infrastructure project.

The hotel, located on a hillside in the port, is used by foreign guests, many of them Chinese project staff, but there were none in the building at the time of the attack, Langove said.

There was no immediate claim of responsibility.

Pakistani officials have said the security forces were on alert for attacks during the Muslim fasting month of Ramadan, which began in early May.

Security across most of Pakistan has improved over recent years following a major crackdown after the country’s worst attack, when some 150 people, most of them children, were killed in an attack on a school in the western city of Peshawar.

But Balochistan, the largest and poorest province, remains an exception and there have been several attacks this year.

The province is rife with ethnic, sectarian and separatist insurgencies, with several militant groups, including the Pakistani Taliban group Tehrik-i Taliban Pakistan (TTP), Balochistan Liberation Army and the Sunni group Lashkar-e-Jhangvi.

Saturday’s incident follows a bombing this week that targeted police outside a major Sufi shrine in Lahore, in the north of Pakistan, that killed at least 10 people and wounded more than 20, officials said.