A massive explosion at a sensitive military area near the Iranian capital city Tehran triggered a series of speculations of a possible air attack.

Social media users circulated images of the explosion at around 00:30 a.m. local time on Friday (08:00 p.m. GMT on Thursday).

Multiple video clips on Iranian social media showed a strong and large orange light, similar to an explosion appearing east of Tehran.

Some residents said they heard a loud sound.

The explosion occurred at the village of Parchin, the site of an Iranian military complex with the same name, located about 30 kilometers (19 miles) southeast of Tehran.

In July 2015, western sources claimed that there was activity in the military complex associated with nuclear weapons. Tehran immediately denied the allegation.

However, the Director-General of the Defense Ministry's Public Relations Office, Second Brigadier General Davoud Abdi, told the Islamic Republic's official news agency (IRNA) that the explosion at Parchin' "public area" was the result of a natural gas tank blast.

By saying “public area”, Abdi effectively ruled out any military facility as the site of the explosion.

"Fortunately, the explosion did not cause any casualties," Abdi added, noting that the firefighters managed to control the blaze resulting from the explosion.

"Our colleagues have reached the area to examine the incident closely," Abdi said, adding that relevant authorities would duly announce further information about the explosion.

Nonetheless, Abdi stopped short of referring to the cause of the explosion.

The Islamic Republic of Iran Broadcasting (IRIB) news agency also attributed the blast to an explosion at a natural gas storage in Parchin, insisting that it occurred at a non-residential area.

According to several reports in state and semi-official media – citing both Abdi and the public relations manager of Tehran emergency, Mir Shahabuddin Ghavami – no emergency services or ambulances were requested in the area following the blast, Reuters reported.

Iranian authorities do not quickly and accurately report security-related incidents and an accurate picture might not emerge for a while.