Health officials say dozens of dead birds discovered Monday along Congress Avenue in downtown Austin posed no health risk to the public.
Air quality tests conducted at the site where the 63 dead pigeons, grackles and sparrows were found have come back negative.
As a precaution, the chief health official for the area, Adolfo Valadez, said some of the birds will be sent to the National Animal Disease Center in Ames, Iowa, and Texas A&M University for further testing.
Valadez said they want to rule out poisoning or viral infections as a possibility. Officials do not believe the deaths were caused by avian flu.
Police closed down the area Monday morning after a passerby found the dead birds at about 3 a.m. All businesses and offices stayed closed and people weren't allowed in to work. Traffic was also heavy because of the 20-block detour.
A Homeland Security spokesman said there is "no credible intelligence'' that suggests a threat against Austin.
New procedures put in place after the Sept. 11 attacks streamlined communications in these types of emergency situations, however rare.
“While this event seems to have taken a long time, really we have brought all of these assets together very quickly to determine what the source of this unusual occurrence or what exactly happened here," APD Assistant Chief David Carter said.
New procedures also involved air monitoring data from the Health and Human Services Department, Valadez said.
Even the Sixth Civil Support team from Camp Mabry arrived at the scene decked out in biohazard suits in their mobile laboratory.
In this situation, one bird was dissected to see if what caused its death could also harm humans, but nothing could be found.
Valadez said one thought is that the birds were poisoned on purpose.