Flames rose more than 80 feet (25 meters) into the air, scorching the tops of coconut and palm trees and sending dense black clouds of smoke into the sky, witnesses said. Villagers ran out of their homes and crowded the streets. Scores of houses and shops were gutted, officials said.
State Finance Minister Yanamala Ramakrishnudu said the death toll rose to 15 when one of the injured succumbed to burn injuries.
Vandana Chanana, a top official of state-run Gas Authority of India Ltd., said 14 other people were injured in the fire in the state's East Godavari district. Doctors said at least five of the injured were in critical condition, company officials said.
Andhra Pradesh Home Minister N. Chinna Rajappa said the explosion occurred at about 5:30 a.m. in Nagaram village, the site of a connecting station for the gas company.
The fire burned for more than three hours before it was brought under control, Rajappa said.
"The extent of damage is being assessed," he said.
Company officials said it was too early to say what caused the explosion. In New Delhi, Oil Minister Dharmendra Pradhan said the federal government has set up a panel to investigate the cause.
Nagaram residents said they had complained that the gas pipelines had not been properly maintained, but were ignored.
"People are angry that GAIL authorities didn't pay heed when they complained that the pipes had become rusty," Ramakrishnudu told reporters.
Residents of neighboring villages were evacuated to safer areas, said East Godavari district collector Neetu Kumari Prasad.
Nagaram is about 560 kilometers (350 miles) east of the state capital, Hyderabad.
Two weeks ago, six people were killed and 29 others injured in an explosion and a subsequent gas pipeline leak at India's biggest government-run steel plant in the central Indian state of Chattisgarh.
Associated Press writer Chonchui Ngashangva in New Delhi contributed to this report.