Maryland Transportation Authority Police officers managed to stop traffic crossing Baltimore’s Francis Scott Key Bridge with less than a minute to spare before the 47-year-old structure came crashing down — felled by the cargo ship Dali in the early hours of Tuesday morning.

Gov. Wes Moore has declared the officers with the Maryland Transportation Authority Police “heroes” for their quick action in the minutes after the Dali’s apparent mechanical failure, crediting them with saving the lives of people who would have driven onto the bridge.

Still, a crew of at least eight Latin American construction workers filling potholes on the night shift didn’t make it off. The Key Bridge collapsed underneath them. Two survived the collapse, while the Coast Guard called off a search for six others Tuesday night and said they were presumed dead.

Since officials managed to halt traffic before the crash, why weren’t they able to clear construction workers off the bridge?

Video, police and fire dispatch audio, ship location data and statements from officials detail the minutes leading up to the Dali’s collision – one of the largest infrastructure disasters in Maryland’s history – but what the workers knew before their tragic fall remained murky Wednesday morning.

At some point as the Dali veered off course in the minutes before impact, its crew signaled mayday, the maritime code for distress. How much time that call gave authorities isn’t clear. A handful of minutes, at the most.