Downey police Lt. Dean Milligan said the shootings occurred shortly after 11 a.m. at a business called United States Fire Protection and at a nearby home, where family members of the owner live. A woman was found dead at the home, he said.
Milligan said police were looking for a gunman who apparently escaped in a black Camaro.
Downey is about 20 miles southeast of Los Angeles. Milligan said the first shooting occurred at the business.
United States Fire Protection Services is in an industrial part of Downey across from a Coca-Cola Co. bottling plant.
The family-owned business sells professional firefighting gear and equipment such as hoses, valves and extinguishers, according to its website.