A Bellevue home belonging to Mariners pitcher Felix Hernandez was severely damaged by fire Monday afternoon. Hernandez and his wife, Sandra, were in Napa, Calif., when flames erupted at the home around 3:30 p.m., but are returning to Seattle because of the blaze, according to his agent, Wil Polidor. He said the couple’s two children were at a mall with their nanny and the pitcher’s mother-in-law when the fire started. No one was hurt in the fire, he said. Firefighting crews from Bellevue, Redmond and Mercer Island spent about 50 minutes knocking down the blaze, said Bellevue Fire Department spokesman Richard Burke. At 6 p.m., investigators were waiting for the house to be ventilated so they could assess damage and begin looking for a cause, he said. Most of the “substantial damage” to the house is on the first floor while the second floor was mostly damaged by smoke, Burke said. No one was in the structure when fire crews arrived. Hernandez in July 2010 paid $3.2 million for the five-bedroom, four-bathroom house, which has about 5,040 square feet of living space. It also has a wine room, four fireplaces, a theater room and lake views.