The Bergen County Prosecutor’s Office is investigating whether a large mansion party in Alpine broke the governor’s limits on gatherings during the coronavirus pandemic. On Saturday, hundreds of partygoers crammed together at a bash, mainly outdoors, at a home on Hemlock Drive from the early afternoon to about 10 p.m., said Alpine Mayor Paul H. Tomasko. He said he does not know the exact number of attendees, but said a majority were not wearing masks or social distancing. He said the party was held by people renting the house with the knowledge of the owner. “Most everyone should be aware...