However, during the subway's main era of decline following the city's 1976 fiscal crisis, there were daily reports of crime. Two hundred were arrested for possible subway crimes in the first two weeks of December 1977 under an operation dubbed "Subway Sweep". Further compounding the issue, on July 13, 1977, a blackout cut off electricity to most of the city and to Westchester. Violence on the subway increased drastically in the last week of 1978, and six murders occurred in the first two months of 1979, compared to nine during the entire previous year. The IRT Lexington Avenue Line was known to frequent muggers, so in February 1979, Curtis Sliwa's Guardian Angels group began patrolling the train during the night. By February 1980, there were 220 Guardian Angels across the system.