Arson investigators are looking into the cause of a fire at a vacant office building north of downtown.
Heavy smoke could be seen coming from the two-story building just before 9 a.m. at West Cypress and Lewis -- just north of I-35 and San Pedro.
Employees from the nursing home next door smelled the smoke and called the fire department.
While the fire did not spread to the nursing home, firefighters took extra precautions to make sure the people inside were safe.
"We didn't evacuate the nursing home, but they did move residents from the portion of the building right next to this," said San Antonio Fire Department spokesman Christian Bove. "(A) heavy amount of smoke ... was coming from the building."
Firefighters managed to knock down the flames from above and keep the fire confined to the upper floor -- where they say it originated.
No one was hurt.