Human error blamed in carbon monoxide leak at Atlanta school ATLANTA (Reuters) - A carbon monoxide leak that sent nearly 50 Atlanta elementary school students and teachers to hospitals was caused by human error when maintenance workers left a boiler valve open, officials said on Thursday. Authorities evacuated the Finch Elementary School on Monday after firefighters detected what they described as the highest levels of carbon monoxide they had ever seen. Students and teachers complained of headaches and nausea and 47 people were transported to nearby hospitals where they were all treated and released, Atlanta Public Schools spokesman Stephen Alford said. Days before the leak, maintenance employees were working on equipment that shared some components with the school's boiler, Alford said. "They left a valve open," he said. The open valve was discovered during an investigation of the leak but the maintenance workers did not come forward with the information, Alford said. "That was a problem," he said. With everything that happened on Monday, we would have wanted them to come forward and at least help us identify what the issue may be. He declined to comment on whether any disciplinary action would be taken against the maintenance workers, saying the investigation is ongoing. A temporary boiler has been installed and officials hope to reopen the school on Friday. They have also installed carbon monoxide detectors, Alford said. "We're going to do that for all of our schools," Alford said, even though Georgia law does not require schools to have detectors. Editing by Kevin Gray and Eric Beech