The incident was a challenge to the religious harmony existing in the state, KCBC President and Archbishop of Thiruvananthapuram Archdioces Soosa Paikam said in a release here.
As the Forest Department had made it clear that they have no role in pulling down the crosses, Soosa Paikiam said the government has the responsibility to find out the "evil forces" behind the act that happened two days back.
He wanted government to order a comprehensive probe to bring the culprits behind the incident.
It was suspected that anti-social elements were behind the incident, he said.