A China Southern Airlines returned to a Zhejiang province airport Wednesday afternoon after passengers and crew members noticed smoke on board.

The CZ6199 plane flew back to Xiaoshan Airport in Hangzhou, the province capital, at 4:40 pm, several minutes after taking off, according to Zjol.com.cn, a news portal of Zhejiang province.

The plane from Daqing, Heilongjiang province, to Guangzhou, Guangdong province, had arrived in Hangzhou earlier that day.

Smoke was seen on a circuit board in the front of the plane, according to a female passenger surnamed Song.

An initial investigation found that the smoke may have been caused by problems with the air-conditioning system, airplane staff said.

No one was injured, and China Southern Airlines has refunded passengers' tickets prices. The cause of the incident remains under investigation.