Hazardous Fumes in Alley Behind 1213 I Street

There was a bit of frightening excitement in the 1200 block of I Street this morning. Two DPW workers were hit hard by a hazardous vapor cloud. The situation is resolved now, but here's how it played out on Twitter:

Haz Mat - 1213 I St NE - 2 DPW workers overcome by fumes from unknown vapor cloud in alley #dcfd
— IAFF Local 36 (@IAFF36) August 27, 2012

Update - 12th & I St NE - unknown vapor cloud in alley, 2 @dcdpw workers decon & eval, hazmat unit IDing product #dcfd
— IAFF Local 36 (@IAFF36) August 27, 2012

Update - 12th & I St NE - hazmat team metering/observing in alley, 2 pts decon & transp to hosp, resident states poss muriatic acid #dcfd
— IAFF Local 36 (@IAFF36) August 27, 2012

Update Final - 12th & I St NE - hazmat team contained/captured product, releasing units #dcfd
— IAFF Local 36 (@IAFF36) August 27, 2012

Here's some info on muriatic acid (also known as hydrochloric acid, which might have been the substance at work here).