Beijing, China (CNN) -- More than 500 fishing boats joined the effort to clean up oil that gushed into a harbor in northeast China when two pipelines exploded Friday, a Chinese state-run news agency reported Monday.
The arrival of the boats in Xingang Harbor in Dalian, China, more than doubled the number that were already on site. They were equipped with oil absorbers and dispersants to help workers clean up an oil slick that had spread across at least 183 square kilometers (71 square miles) off the coastal city in Liaoning Province, the Xinhua news agency said.
The cleanup effort focused on an area south of Dalian's Golden Pebble Beach and east of Bangchui Island.
Strong winds on Sunday helped limit the oil's spread, said Luan Yuxuan, deputy director of Dalian City's Oceanic and Fishery Administration. He predicted Monday that cleanup operations would last at least four to five days.
In all, 24 oil cleanup vessels and 800 fishing boats were engaged in the effort and 460 tons of oil had been collected, he said Monday.
Officials did not know how much oil had been spilled, he said.
Ship traffic at Dalian, China's second-largest port for crude oil imports, was limited so as not to interfere with the cleanup efforts, said Wang Ning, a senior engineer with the maritime affairs bureau of Liaoning Province.
Xingang port was engulfed in flames Friday night when an oil pipeline exploded. That caused an adjacent pipeline to explode, too. More than 2,000 firefighters and 338 fire engines from 14 cities across Liaoning Province worked through the night to put out the fire, Xinhua said.
No one was hurt.
A team was established Sunday morning to investigate the incident.