ADEN (Reuters) – Civil defense forces in Yemen’s port city of Aden fought to extinguish a fire at an oil refinery on Friday, sparked hours earlier by an explosion, the cause of which was still unknown, the refinery company said.

There were no reports of casualties.

Separately, Saudi state television reported that the Saudi-led military coalition fighting the Iran-allied Houthi group had destroyed a communication and control center the Houthis used to direct their unmanned aircraft. It did not give further details.

A day earlier the Houthis launched a drone attack on a military parade in Lahaj, a province next to Aden, killing several people.

Aden is under the control of an internationally recognized government, which, backed by a Saudi-led and U.S.-backed coalition, is fighting a nearly four-year-old war against the Houthis.

The Houthis said in November they were halting drone and missile attacks on Saudi Arabia, the United Arab Emirates and their Yemeni allies, but tensions have risen recently over how to implement a United Nations-sponsored deal in Hodeidah.

The Houthis and the government agreed at peace talks in Sweden in December to stop fighting in the Red Sea port city of Hodeidah and withdraw forces following months of diplomacy and Western pressure.

But implementation of the deal, the first breakthrough in peace efforts in five years, has stalled as the sides disagree on who will control Hodeidah after the withdrawal.

The U.S. State Department condemned Thursday’s attack and called for restraint from all sides.

“This attack contravenes the spirit of the (Hodeidah) ceasefire and the progress made last month at the U.N.-led talks in Sweden,” deputy spokesman Robert Palladino said in a statement.