The mall that borders the convention center was evacuated, The Philadelphia Inquirer reported. Trains in the area were also halted.
K9 units were sweeping the shopping center and said shortly before 3pm that no device had been planted, Philly Voice said.
On Thursday evening, police confirmed that they were investigating an alleged plot to attack the center where the election ballots are being counted.
A tip came in that an individual or a group was travelling to the city from Virginia in a Hummer with the intention of attacking the election location.
A man was taken into custody and a weapon recovered. It is unclear whether the two incidents are connected.
The eyes of the nation are on Pennsylvania as workers continue to tally thousands of ballots that could decide the presidential election.
Mr Biden is currently leading the president by nearly 14,000 votes in the state. If Mr Trump loses Pennsylvania there is no path back to the White House for him.