Six persons were held in Thrissur on Tuesday with hashish oil worth crores. One kg of hashish oil was seized from them, the police said. The six, including four from Kunnamkulam, one from Thiruvananthapuam and one from Kollam, were arrested from the Thrissur railway station. The accused had attempted to smuggle the contraband in a steel flask. They confessed that the hashish oil was brought from Andhra Pradesh.