Mumbai Police are trying to trackdown at least 150 persons who participated in the congregation organised by Tablighi Jamaat in Delhi's Nizamuddin area last month and returned to the city, an official said on Wednesday.The congregation, attended by people from across India as well as other countries, was later found to have been a coronavirus hotspot.Search is on now for the participants who left Delhi so that they can be tested for infection and quarantined if necessary.The city police had recently received a list of at least150 people who attended the event and returned to Mumbai, said an official.The police are trying to trace them and also find out their travel history after the congregation and the people they came in contact with, he said.Once they are traced, their samples would be sent for testing, he said.As many as 32 persons including 12 Indonesian nationals who attended the Nizamuddin event and later traveled to Mumbai have been quarantined.