A 70-year-old radio journalist was in stable condition Tuesday after masked men barged into his studio and set fire to it while he was on the air.

Authorities said three men were arrested in Monday's attack on Fernando Vidal but were refusing to talk.

Vidal was interviewing two women in Yacuiba, a city of 120,000 that borders Argentina, about alleged corruption among customs police when three masked men entered the studio of Radio Popular at midday, said his son-in-law, Esteban Farfan.

One splashed around gasoline, another set it alight and a third fired shots in the air, police said. Vidal was burned as he tried to intervene.

He was in intensive care Tuesday, in serious but stable condition with second-degree burns on his face and arms, at a hospital in the eastern city of Santa Cruz Tuesday, said his doctor, Javier Palenque.

A station technician, Karen Arce, also suffered less serious burns in the attack. She was driven the six hours with Vidal to Santa Cruz on Monday evening.

Vidal is a former Yacuiba mayor who uses his daily radio program to denounce corruption in a city that is along a cocaine smuggling route and where trade in contraband is rampant.

"My father-in-law knows the identity of the people who ordered this act," said Farfan. "There are political interests that want to silence the radio station. We will name names at the appropriate time."

Interior Minister Carlos Romero told reporters that the three suspects arrested in the attack "have remained silent."

He said one was a mechanic and one a taxi driver and neither they nor the third man arrested " would have had direct motives for attacking the radio station.

"There is surely someone else behind this and that's what we're investigating," Romero added.