MANILA (Reuters) - The husband of a woman working at a Chinese consulate in the Philippines shot dead the deputy consul general and a senior staff member at a birthday lunch on Wednesday and wounded the consul general, police said.

In a bizarre drama police have yet to unravel, waiters at a popular Filipino-food restaurant in the central city of Cebu said they heard shouting from a private room but could not understand what the argument was about, officers said.

Minutes later they heard gunshots.

Consul General Song Ronghua was rushed to hospital, Chief Superintendent Prudencio Banas said, adding that the Chinese suspect, Li Qing Liang, was arrested and his wife, Guo Jing, who works in the visa section, was held for questioning.

It was not immediately clear whose birthday was being celebrated. Police, who supplied the English names of the suspects and victims, earlier said Guo Jing was the main suspect. "We're still trying to determine the motive for the shooting," Banas said.

Superintendent Marciano Batiancela said the consul general was in stable condition. His male deputy, Sun Shen, was shot in the neck and finance officer Li Hui, a woman, was shot in the head. Both died.

Police said the suspect and his wife had invoked diplomatic immunity after they were found at the consulate and taken in for questioning. A gun, a calibre-45 pistol, was found at the scene.

The foreign ministry and China's embassy in Manila declined to comment and were trying to gather more details.