Several motorists and pedestrians interrupted the interview to offer help to him and his family, who are staying with relatives.
Crespo and his wife have two children, 6 and 9, and had lived in the home since 1999. The pet cat is missing.
"We lost everything," he said.
The Burlington County Prosecutor's Office is investigating the fire. Spokesman Joel Bewley said there would be no other comment at this time. The county fire marshal also is looking into the blaze.
Crespo, a landscape contractor, said he had planned to convert the duplex, in the 400 block, into a single-family home.
First elected in 2006 with two running mates, Crespo helped the Republican Party gain control of the council for the first time in decades. But later that year, he had a falling-out with the Republicans and became a Democrat.
For five years, he served as council president, and was no stranger to controversy.
"I hold people to the fire," he said, explaining that some employees were fired for failing to do their jobs.
In 2008, a municipal judge found former School Board President Robert Thibault, then the vice president of the local Republican committee, guilty of harassing Crespo. Thibault admitted leaving a profanity-laced message on Crespo's cellphone calling the council president a dead man.
Thibault, who later became a councilman, was fined, but questioned Crespo's waiting five months to press charges on the eve of an election. Thibault did not return a call for comment.
Also that year, other Republican council members accused Crespo of secretly recording conversations.
In 2010, his truck appeared to be wired with a suspicious device when it was parked in front of his house, Crespo said Tuesday.
At the time, police evacuated the block and investigated what they believed was an incendiary device attached to the vehicle. The Prosecutor's Office also launched a probe but would not comment on its findings.
In June, Crespo was defeated in the Democratic primary. He blamed interference from local Republicans. Last month, he was appointed to an unexpired term when another councilman resigned.
Contact Jan Hefler at 856-779-3224 or firstname.lastname@example.org, or follow on Twitter @JanHefler. Read her blog, "Burlco Buzz," at www.philly.com/BurlcoBuzz