The victim, named as Rahul Meswaniya, was attacked by the big cat late on Tuesday on a road near Vavdi village in Amreli district next to the lion reserve at Gir National Park.
Forest official Jayan Patel said the lioness was put in a cage after the attack and an investigation has been launched.
“The lioness belongs to the non-protected area and it is likely that the boy was attacked because he was reportedly running and the animal must have seen it as an attack on her,” Mr Patel told The National.
Mr Patel said the area of the attack falls under a buffer zone about 30 kilometres from the main park, which has about 35 lions.
He said it was likely the teenager was unfamiliar with the wildlife because he was from a family of migrant workers.
“There are a dozen villages next to the region and people co-exist with the animals as they have been [educated] about the lions,” Mr Patel said.
Gir National Park is spread across about 1,400 square kilometres, but only 260 square kilometres is a protected area for the endangered cat species.
The big cats were once on the verge of extinction, but conservation efforts have helped their population grow from 523 in 2015 to 674 in 2020.
Lion sightings are common in the villages around the forested area where the animals often prey on pigs and cattle.
But as the big cats' population increased in recent years, there are frequent instances of lions attacking people.
An 18-year-old worker returning from his farms was killed after being attacked by a pair of lions in the same district in July, about a month after a five-year-old girl was mauled to death outside her home and her body dragged to the forest by one of the animals.
There are no consolidated government figures on human casualties.
Rajdeepsinh Jhala, deputy conservator of forests in Gir, said the expansion of human settlements near by and a lack of space for lions in the park were partly to blame for the increased conflicts.
“Human activities have grown in the past few years," he told The National. "There are more and more people living near the forests, which were not traditionally human settlements.
“The population of lions is also growing. One lion needs 20 square kilometres, but then lions live in prides of 25. Now lions are straying out of the forest as they try to make new territory. They feed on cattle and feral animals.”
The space crunch is also endangering the lions, with 313 deaths reported between 2018 and 2020, including 23 in traffic accidents and falls into wells.
Last week, a lioness was rescued after it fell into an open well on a farm near the park.