Syrian media has reported a large explosion at a Syrian military base near the Iraqi border.

The U.K.-based civilian watchdog group Syrian Observatory for Human Rights (SOHR) reported that at least five pro-Iranian militants were killed in the aerial drone attack that struck several facilities at a military base in the Al-Bukamal region of Syria.

According to the report, eyewitnesses told SOHR the drones had struck a facility belonging to the Lebanese terrorist group Hezbollah.

The Al-Bukamal area is where Iran is building its massive Imam Ali base just a short 50 kilometers from the border with Israel. The Iranian regime has been making its presence known in Syria for years, but this planned military base being constructed in Syria is the largest one to date.

Syrian media reported separately on Monday that air defenses intercepted on Sunday “hostile missiles coming from the occupied lands.”

Some reports indicate that that the missiles that weren’t intercepted hit weapons storage sites that were believed to house Iranian drones and missiles. The SOHR said that three “foreign citizens” were killed in the Sunday night attack.