(Philadelphia Police)

A Muslim group in Philadelphia is offering a $20,000 reward for tips leading to the arrest of criminals who have been dressing up as Muslim women.

A string of bank robberies and a homicide committed by men dressed as Muslim women has inspired the Majlis Ash Shura, a group representing Philadelphia-area Muslim congregations,  to put up the reward.

"Philadelphia is a unique city in that Islam is not new here," Aliya Khabir, a spokesman for the United Muslim Masajid, said.  "It's up to us to set the tone for how this is addressed."

Police are searching for suspects in five bank robberies and a murder in which a man wearing a veil similar to those worn by conservative Mulsim women shot and killed a barber at a barber shop outside of the city, according to ABC News affiliate WPVI.

"We are seeing this all too often now,  cowards dressing in the outer garb of Muslim women, robbing banks, shooting people," said District Attorney Seth Williams.

A suspect in the murder case has been arrested, but police are still searching for at least two other suspects for the bank robberies. The suspects are  described as two black males with thin builds, approximately 5-feet-10. The men were seen in surveillance video wearing loose dark-colored dresses and head coverings, according to the Philadelphia police department.

Authorities do not think that the crimes are the work of a single group, but rather individuals adopting the same strategy.

Imam Asim Abdul Rashid, of the group that is sponsoring the reward, said Tuesday the the crimes are endangering members of the Muslim community.

"It puts our women in danger and it puts a black mark on our community in general," he said.