The extermination of rats at a homeless encampment in Harrisburg is expected to start on Wednesday.The city said the area under the Mulberry Street Bridge has been cleaned up, but a few people are still in tents.The city is trying to convince those people to leave.If they choose not to move, the city will consider putting up temporary fencing, so the public works team and park rangers have access to the area to begin exterminating rats. Related video below: Cleanup begins at Harrisburg homeless encampment