Rebels attacked a hospital in Congo and killed at least 13 people, including infants and patients, according to hospital and military officials. The Congolese army said three attackers were killed when the military intervened.

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Some hospital staff are missing and several houses were burned in the attack Thursday night on the medical center in Lume, North Kivu province. It's the largest health facility in the region.

Among those killed in the attack were three infants and four patients, hospital chief Kule Bwenge told reporters.

“Four blocks of the medical center were set on fire. Several sick guards, as well as a nurse, are missing,” he said.

The reason for targeting the hospital was unclear.

In the nearby village of Kidolo, four other people were killed with machetes and shot, apparently as part of the same attack.

North Kivu military spokesman Anthony Mualushayi said the attackers were Mai-Mai militia members from the Dido group. In addition to the attackers who were killed, one was captured in the ensuing clashes, he said.

But local civic groups accused rebels of the Uganda-based Allied Democratic Forces, or ADF, of carrying out the attack. ADF rebels have been active in eastern Congo for decades and have killed thousands in the region since they resurfaced in 2013.

Other attacks were reported last week in the nearby towns of Bulongo and Kilya, also in North Kivu.

North Kivu is in eastern Congo and borders Uganda and Rwanda. Eastern Congo sees daily threats from armed groups battling for the region’s rich mineral wealth, which the world mines for electric cars, laptops and mobile phones.