Updated

Federal regulators say they're investigating a lag of about 45 minutes between an ammonia leak at a refrigeration plant and the first siren blasting an offical warning to area residents.

Millard Refrigerated Services, based in Omaha, Neb., says it detected the leak at its Theodore plant that freezes chickens at 9:05 a.m. Monday and alerted authorities within 20 minutes.

The Mobile County Emergency Management Agency said Wednesday it got a 911 call at 9:25 a.m. and the first outdoor siren was activated at 9:50 a.m. Officials say they acted as quickly as they could.

Some residents complained the lag left them unaware as ammonia escaped the plant. Some 130 people sought medical attention for breathing problems and one remained in intensive care Wednesday.