It had already been an eventful day in Iran: The country had just launched missiles at United States forces based in Iraq and an airliner carrying at least 176 people crashed shortly after takeoff from Tehran on Wednesday, killing everyone on board.

Then just before dawn, a 4.5-magnitude earthquake struck southern Iran at a depth of about six miles, the United States Geological Survey reported, in the same region as the troubled Bushehr nuclear power plant. It struck just as Iranian leaders were trumpeting their strike on two Iraqi bases housing United States forces, in retaliation for last week’s American drone strike that killed Maj. Gen. Qassim Suleimani, commander of Iran’s elite security and intelligence forces.

No casualties were immediately reported, but rescue teams were working at the site, Jahangir Dehqani, managing director of the Bushehr crisis management agency, told the state-run IRNA news agency.

The quake was reported about 30 miles from the Russian-built Bushehr nuclear plant. The plant, which is monitored by the International Atomic Energy Agency, has long been seen as a safety concern by Western countries. It has been plagued by construction delays and technical problems, and is on an active fault line. Experts have feared that could lead to an accident on the scale of the Fukushima disaster in Japan, or even Chernobyl.