(AP) — Bomb-carrying drones targeted an Iranian defense factory in the central city of Isfahan overnight, authorities said early Sunday, causing some damage at the plant amid heightened regional and international tensions engulfing the Islamic Republic.

The Iranian Defense Ministry offered no information on who it suspected carried out the attack, which came as a refinery fire separately broke out in the country’s northwest and a 5.9-magnitude earthquake struck nearby, killing two people.

However, Tehran has been targeted in suspected Israeli drone strikes amid a shadow war with its Mideast rival as its nuclear deal with world powers collapsed. Meanwhile, tensions also remain high with neighboring Azerbaijan after a gunman attacked that country’s embassy in Tehran, killing its security chief and wounding two others.

Details on the Isfahan attack, which happened around 11:30 p.m. Saturday, remained scarce. A Defense Ministry statement described three drones being launched at the facility, with two of them successfully shot down. A third apparently made it through to strike the building, causing “minor damage” to its roof and wounding no one, the ministry said.

Iranian state television’s English-language arm, Press TV, aired mobile phone video apparently showing the moment that drone struck along the busy Imam Khomeini Expressway that heads northwest out of Isfahan, one of several ways for drivers to go to the holy city of Qom and Tehran, Iran’s capital. A small crowd stood gathered, drawn by anti-aircraft fire, watching as an explosion and sparks struck a dark building.

“Oh my God! That was a drone, wasn’t it?” the man filming shouts. “Yeah, it was a drone.”

Those there fled after the strike.

That footage of the strike, as well as footage of the aftermath analyzed by The Associated Press, corresponded to a site on Minoo Street in northwestern Isfahan that’s near a shopping center that includes a carpet and an electronics store.

Iranian defense and nuclear sites increasingly find themselves surrounded by commercial properties and residential neighborhoods as the country’s cities sprawl ever outward. Some locations as well remain incredibly opaque about what they produce, with only a sign bearing a Defense Ministry or paramilitary Revolutionary Guard logo.

The Defense Ministry only called the site a “workshop,” without elaborating on what it made. Isfahan, some 350 kilometers (215 miles) south of Tehran, is home to both a large air base built for its fleet of American-made F-14 fighter jets and its Nuclear Fuel Research and Production Center.

Separately, Iran’s state TV said a fire broke out at an oil refinery in an industrial zone near the northwestern city of Tabriz. It said the cause was not yet known, as it showed footage of firefighters trying to extinguish the blaze.

State TV also said the magnitude-5.9 earthquake killed two people and injured some 580 more in rural areas in West Azerbaijan province, damaging buildings in many villages.