Updated

Carbon monoxide detectors will be placed in an Atlanta elementary school where dozens of students were sickened after two workers failed to reopen a boiler valve.

Associate superintendent Steve Smith says Georgia law does not require the detectors in schools. But Atlanta Public Schools is planning to install them district-wide.

Meanwhile, administrators say it appears the leak was caused by human error, not an equipment failure. More than 40 students and several adults at Finch Elementary School were treated at hospitals after Monday's leak.

Officials said at a news conference Thursday that two maintenance workers serviced the boiler identified as the leak source at the southwest Atlanta school just days before the leak. Officials say the leak occurred after they failed to reopen a valve after doing the work on Friday.