Informant Z told drug investigators that Maxy Mum had sold her cocaine on numerous occasions. The agents asked Informant to arrange another sale with Maxy, and it took place on the sidewalk outside Maxy's apartment. The agents witnessed the transaction from a remote location. After later confirming that the substance sold by Maxy was cocaine, the agents asked Informant to arrange another sale for the next day to occur inside Maxy's apartment. At the appointed time, Informant went into the apartment. She came out 15 minutes later and informed the agents that the sale had occurred and that a large quantity of cocaine remained on the premises. Fearing that the contraband might be sold off to others, the agents moved in immediately, arresting Maxy and seizing the cocaine. Was this warrantless action lawful?