Story highlights

NEW: United States begins delivery of promised anti-tank weapons, source says

Blast from ISIS fighter's tank sets off second explosion near stack of ammunition

The commander of an Iraqi brigade is among the wounded, security officials said

Baghdad, Iraq CNN  — 

At least 34 Iraqi police officers were killed and at least 48 more wounded Monday when an ISIS fighter drove a tank rigged with explosives into a joint Iraqi security forces base about 28 kilometers (17 miles) southwest of Samarra, two security officials told CNN.

The attack happened at 3 a.m. local time. A medical source at a Balad hospital confirmed the deaths and number of those injured.

Security officials said guards stationed at the base’s entrance fired at the tank but couldn’t stop it.

The tank shoved aside two Humvees that blocked the entrance just before the ISIS driver detonated the tank. That explosion, near a stack of ammunition, triggered another blast. The commander of an Iraqi brigade is among the wounded, the officials said.

Reinforcements were sent to the area from the Iraqi Federal Police force, which is based near Samarra in north-central Iraq.

Also on Monday, a defense official told CNN the United States has begun deliveries of promised anti-tank weapons to Iraq to help forces combat ISIS’ use of heavily armed vehicles.

The United States promised 2,000 AT4s. According to the official, all have now arrived, although the official declined to say exactly where.

Of the 2,000, 1,000 were provided to the government of Iraq. The U.S.-led coalition is taking the unusual step of keeping control of the remainder, which will be used for training “and for contingencies,” the official said.

CNN’s Hamdi Alkhshali reported from Baghdad, and CNN’s Ashley Fantz wrote from Atlanta. CNN’s Barbara Starr also contributed to this report.