A boat held by Somali pirates was freed after a gun battle, fishermen and witnesses said Sunday, asserting that several of the pirates were killed.

There was no precise information about the boat or the fate of its crew, whether international forces were involved in the rescue or whether the crew had wrested back control on their own.

However, security sources said the boat was believed to be an Iranian fishing vessel seized earlier this week with 15 crewmembers and held off the central Somali coastline.

“We heard heavy exchange of gunfire. … Several of the pirates were killed and a boat they hijacked was freed,” Muktar Yakub, a fisherman in the Harardhere area, told AFP.

He said the boat has disappeared from sight of the coast.

Piracy peaked in 2011, when Somali pirates held more than 700 hostages, but the attack rates have tumbled, partly thanks to the posting of armed guards on boats and navy patrols. Eperts have warned that rampant illegal fishing by foreign trawlers off Somalia is threatening economic gains and could push communities back to maritime crime.

Although illegal fishing was used by many pirates as an excuse for attacks — with an array of vessels seized, including yachts, oil tankers and container ships — the issue could encourage a fresh round of piracy.

Dozens of hostages remain in pirate hands. They include 26 sailors on the now wrecked fishing boat Naham 3, who have been held since March 2012.

Two Iranian fishing boats were seized in March near Ceel Hur in central Somalia, but one of them escaped in August.

The other, the Siraj, is still being held. Fifteen crewmembers are being held onshore; local authorities freed four others earlier this month.