apalachin arrests. on what grounds?

in the 50’s , i think, the police in apalachin, in new york, were tipped off about a big meeting of crooks. upon what legal grounds (or pretext) did they go to raid the meeting? did they have a warrant?

In 1957 about 100 of the top mobsters from across the country were going to meet in Apalachin, their first big meeting since 1946 in Havana. They thought it wouldn’t be noticed but mass rental of motel rooms and large meat purchases alerted New York State Police Sargeant Edgar D. Crosswell that something was up. He set up roadblocks outside the home of Joseph Barbara where the meeting was underway. The hoods saw the roadblocks, many panicked and ran for the woods, and 60 ended up being arrested. Those who stayed in the house were not bothered. $300,000 cash was seized from those arrested. No crime had been committed but a number of convictions for obstruction of justice were obtained.

Bear in mind that the cops had a lot more leeway and power back in 1957.