One person was killed and another was seriously wounded in Nassau County on Wednesday after being shot by a gunman who was angered over a business deal gone bad, the authorities said.

The gunman, who fled and set off a manhunt, was identified by the police as Sang Ho Kim, 63, of Fresh Meadows, Queens.

The shooting occurred just after 10 a.m. at a light fixture company on South Street in East Garden City, N.Y., only blocks from the Roosevelt Field mall. Shortly after, there was a strong police response.

Streets were closed, shoppers were screened as they left the mall, schools were locked down, and vehicles were stopped and searched. With a recent bloody terrorist attack on a mall in Kenya and a mass shooting at the Washington Navy Yard still in the news, many residents were alarmed when they saw the burst of law enforcement activity.