(CNN) -- Lehigh County Coroner Scott Grim's office normally responds to calls of motor vehicle accidents, homicides or other incidents that require determination of a cause of death. Thursday brought something totally unexpected.
A large sinkhole spread into a historic cemetery in Allentown, Pennsylvania, prompting officials to get a court order to allow exhumations of graves if Grim deems such action necessary.
About 60 graves in Union and West End Cemetery are threatened and were roped off, Grim told CNN.
Many of the burials were in the 1880s, with at least one as far back as 1858.
"If we go back there tomorrow and see a shift or collapse in soil or ground, or if any sites are in jeopardy, than we are going to have to make that decision to excavate," the coroner said.
A dozen homes on nearby 10th Street were vacated and 25 people evacuated because of the sinkhole, said Allentown Fire Chief Robert C. Scheirer. The sinkhole was likely caused by a water main break.
A judge gave officials a conditional go-ahead to do the exhumations.
"It's a very sensitive issue. You are dealing with a cemetery," Grim told CNN. "You are laid to rest and now it is being disturbed."
Several headstones have tilted and there were some breaks in the cemetery ground. Most of the graves are from the late 1800s to early 1900s, officials said.
"We can see depressions where the ground has fallen as much as two feet," said Everette Carr, president of the Union and West End Cemetery Association, which maintains the 157-year old nonprofit burial ground.
"It's a very volatile situation," Carr said. "The ground is unstable. There is no question it is moving."
There also could be unmarked graves, said Carr.
Because of their age, some of the graves may have few remains in place, he added.
The cemetery holds about 20,000 graves, including 714 Civil War veterans, whose graves are located across the cemetery. Among them is a Medal of Honor winner, Ignatz Gresser.
Carr did not know if any of the threatened graves included soldiers. Grim, whose office photographed the 60 markers, said he saw some belonging to soldiers.
Cemetery volunteers previously did a survey, but there are no detailed historical records of the dead beyond those whose graves have headstones. And some of those are difficult to read, Carr said.
The coroner said he was in touch Thursday with a forensic archaeologist and anthropologist to learn more about burial practices of the period.
"During that era, people were buried in a wooden casket or some were buried in a brick-type casket," Grim said.
None of the graves appeared to be open.
The calamity also was affecting the living.
At least two residential structures nearby suffered serious damage from the sinkhole.
"Once we get the street secured, we will get into these homes and determine whether any have to be razed," Scheirer said.
The fire chief estimated the sinkhole to be about 50 feet long and 30 feet wide. "They are pumping concrete into it right now," he said.