Thousands of people left the JPMorgan Chase & Co. complex and only later did investigators figure what the device was: a timing device used to keep presentations short. Chase spokesman Jeff Lyttle says the lights warn a speaker when it's time to wrap up.
Fire officials say several people were overcome by summer heat in the parking lot during Tuesday's evacuation and were treated by paramedics.
The Columbus Chase complex houses more than 8,000 employees.
