Was it a gas leak? Neighbors worried they might be affected.
In the end, officials determined that the deaths of hundreds of birds had been deliberate, caused by a DEP-approved granular pesticide used to control blackbirds.
They were feasting on his young corn, so farmer Richard Ingraldi - seeking to protect his crop - decided to cull their numbers, county spokesman Troy Ferus said.
"I walked around the neighborhood and saw a couple [dead] birds in a yard," Ferus said. "But there were a couple hundred in the farm field.
"It was an odd, odd thing," he said.
Most blackbirds who ate the pesticide died on the farm, but others flew a short distance and fell in the surrounding community, the spokesman said.
Before the cause of death was known, a recorded phone message went out to community.
"Millville police are asking all residents to stay indoors due to an odor and death of several birds in the area," it said.
A subsequent message informed residents about the cause of death and advised them how to safely dispose of the birds.
Ferus and DEP spokesman Larry Hajna said no violations had been committed. The farmer had applied the pesticide, Avitrol, in the approved fashion, they said.
It's used to control various species of blackbirds and starlings, and poses no threat to consumers when employed correctly, Hajna said.
Ingraldi could not be reached for comment. Representatives of the New Jersey Audubon Society declined to comment.
"The mystery is solved," Hajna said. "It was a weird one."
Contact Edward Colimore at 856-779-3833 or firstname.lastname@example.org.