Dogs killed six protected deer in a zoo in southwest China's Yunnan Province on Monday, zoo management said Friday.

Four dogs got into the Yunnan Wildlife Zoo and killed four spotted deer and two fallow deer. Another two deer and an emu were seriously injured, said Tang Yangchun, head of the zoo's animal management department.

Tang suspected some people were behind the attack. "The gates were guarded round the clock. And the dogs couldn't have climbed over the 2.5-meter zoo fence by themselves."

The dogs, which were captured or killed by zoo workers, seemed well-fed and trained to kill, Tang said.

Guards say the dogs first cornered the deer before attacking them as pack.

The dead state-level protected deer were buried after disinfection. The injured animals are being treated.