Naval forces off the coast of Somalia have exchanged gunfire with armed men on board a hijacked oil tanker after trying to intercept a boat believed to be carrying supplies, officials said.
Puntland forces tried to stop the boat as it headed towards the vessel where eight people are being held hostage.
Four people were wounded in the incident, the BBC has learned.
The oil tanker was seized on Monday while en route from Djibouti to the Somali capital, Mogadishu.
It is the first hijack off Somalia's coast since 2012.
The director general of the Puntland maritime force, Abdirahman Mohamud Hassan, said that "pirates" on board the tanker opened fire after authorities tried to intercept a boat believed to be carrying essential supplies, such as food.
"Pirates on the ship fired on us and so the pirate boat escaped," the director general told Reuters news agency.
Ali Shire Mohamud Osman, the district commissioner in the town of Alula, near where the ship has been taken, told the BBC that four people were wounded following the incident on Thursday, but did not provide further details.
The Puntland authorities have deployed local forces in the area in an attempt to assist in rescue efforts for the hostages on board the vessel, the district commissioner said.
The vessel was carrying oil and was owned by the United Arab Emirates (UAE), despite conflicting reports over the flag it was sailing under, he added.
On Wednesday, the European Union anti-piracy naval force, which is helping to tackle piracy in the region, said the hijackers were demanding a ransom.
Authorities are still trying to determine whether the gunmen, who have not given any details about the size of the ransom, are fishermen or organised pirates.
The EU force earlier made contact with the ship's master, who said his vessel and crew were being held captive anchored off the coast of north-east Somalia. The ships tracking system has reportedly been switched off.
The gunmen have told a local official that they are fishermen whose equipment was destroyed by illegal fishing vessels.
The Sri Lankan foreign ministry has confirmed that eight of its nationals are on board the vessel.
Piracy off the coast of Somalia, usually for ransom, has reduced significantly in recent years, in part because of extensive international military patrols as well as support for local fishing communities.
At the height of the crisis in 2011, there were 237 attacks and the annual cost of piracy was estimated to be up to $8bn (£7bn).
However, some smaller fishing vessels have recently been seized in the area.
In 2015, Somali officials warned that piracy could return unless the international community helped create jobs and security ashore, as well as combating illegal fishing at sea.
Some Somali fishermen turned to piracy after their livelihoods were destroyed by illegal fishing from foreign trawlers, which benefited from the lack of a functioning coastguard in the country following years of conflict.
