At least four people were killed on Tuesday and several others wounded in a gunfire near a mosque, the Omani police said.
The attack took place early on Tuesday in Wadi al-Kabir, a district east of the capital city, Muscat, as Muslim Shiites were carrying out a religious ritual.
The security forces took the necessary measures to calm the situation, the police added.
Two Pakistanis were among the fatalities, the Pakistani embassy in the country said.
Oman, which is located on the Arabian Peninsula, is considered one of the safest countries in the Arab world and is popular with foreign tourists.
In a video purporting to show the incident, dozens of people can be seen fleeing the Imam Ali Mosque as the sound of repeated gunfire could be heard. It remained unclear whether one or more gunmen opened fire.
“The authorities are continuing to gather evidence and conduct investigations to uncover the circumstances surrounding the incident,” police said on X.