An explosion that rocked the northeastern city of Zarqa early Friday was caused by a chemical reaction inside a shell in a warehouse containing unusable mortar shells, according to the Jordan Armed Forces-Arab Army (JAF).

No injuries were reported, only minor material damage to some old machinery, according to officials.

Minister of State for Media Affairs Amjad Adaileh said that the explosion occurred at a Jordan Armed Forces-Arab Army (JAF) warehouse containing unusable mortar shells.

He said that initial investigations pointed to a short circuit in the warehouse, located in the Ghabawi area, east of Zarqa, in an isolated and uninhibited area.

However, the army announced that the explosion was due to a chemical reaction in one of the mortars, caused by an increase in temperatures due to the heatwave currently impacting the Kingdom. 

The JAF also urged the public to exercise caution and avoid rumours shared by some media outlets and social media pages, noting that the army is "the only reliable source” for any information related to the incident.

JAF's director of engineering Brig. Gen. Emad Al Khamaiseh on Friday announced on Jordan TV's morning show that "the area has been completely scanned for any dangerous residue” and that the situation was "under control”, urging the public to avoid the area.

On Friday morning, Chairman of the Joint Chiefs of Staff Maj. Gen. Yousef Huneiti visited the site of the blast and checked on the army's measures taken in cooperation with the concerned authorities to isolate the area, put out the fire and disinfect the area, and scan for any residual materials.

"The swift response and high professionalism in dealing with the explosion in record time minimised losses,” said Huneiti.

Following the blasts, citizens reported that they heard sounds "like small explosions still taking place". 

"I heard the sound of an explosion, followed immediately by a second loud one. I went to the roof of my building and saw a fire in the distance," a witness, who preferred to remain anonymous, told The Jordan Times at the time of the explosion.

Videos also went viral on local social media pages, as people captured images and footage of flames lighting up the night sky.

The blast occurred at around 1am, by the time the night-curfew hours had started and people called each other as they were unable to leave their houses and check what had happened.

By Friday morning, the concerned authorities had closed the Ghabawi area to manage the situation