JUBA, South Sudan (AP) — Witnesses say clashes between rival factions of South Sudan's army are continuing in the capital, with major blasts being heard.

An aid worker in the Tomping area of Juba, where the airport and a U.N. base are located, described a "massive explosion" early Monday.

A resident in the Gudele area of Juba said there were explosions and heavy gunfire. The witnesses spoke on condition of anonymity, citing safety concerns.

The U.N. mission in South Sudan said on Twitter that clashes restarted near its compound in Jebel, where about 30,000 civilians have taken refuge.

Shantal Persaud, a spokeswoman for the U.N. mission, said a Chinese peacekeeper was killed Sunday night at the base.

Jason Patinkin reported from Nairobi, Kenya.