There was no immediate word on casualties, but several ambulances were rushing to the site of the crash, their sirens wailing. Security forces have cordoned off the area where the plane went down in southern Sanaa.

The official said military experts were investigating the incident.

He spoke on condition of anonymity in line with military rules that prohibit personnel from speaking to the media without prior authorization.

In February, a military plane flying a training mission crashed in Sanaa, killing 10 people and destroying two houses.

Speaking in a press conference in the Yemeni capital of Sanaa, Interior Minister Abdel-Qader Kahtan said a Yemeni investigation found that the weapons were destined for armed insurgents. He did not elaborate, saying only that an investigation is ongoing.

He said he had hoped Iran would not “export weapons to Yemen”. It was the first acknowledgement by a Yemeni official on the record to hold Iran responsible for the shipment.

The U.S. State Department said in a statement that the initial findings of the Yemeni investigation show that “Iran continues to defy the international community through its proliferation activities and support for destabilizing action in the region.”

The State Department said Yemeni government officials noted that their investigation thus far shows that the weapons were loaded onto the vessel in Iran.

Kahtan’s statement came days after Yemen asked the U.N. Security Council to investigate the cargo of Iranian-made missiles, rockets and other weapons. Yemeni President Abed Rabbo Mansour Hadihas warned Iran to “stop meddling” in the affairs of his country, which has for years been fighting Shiite Muslim insurgents near the country’s border with Saudi Arabia.

Yemen’s Defense Ministry first announced in a statement Wednesday that the country’s authorities seized the Iranian ship last month, carrying material for bombs and suicide belts, explosives, Katyusha rockets, surface-to-air missiles, rocket-propelled grenades and large amounts of ammunition. Iran is governed by Shiite clerics.

The U.N.’s envoy to Yemen has not confirmed allegations that the shipment was loaded in Iran, saying that is up to a U.N. investigation to determine.