First a Sweet 16 party, now a wedding and a birthday: Long Island has more superspreading events.

Health officials on Long Island were scrambling on Wednesday to respond to two coronavirus superspreader events that left 56 people with the virus and nearly 300 in quarantine after attending a wedding and a birthday party.

The birthday party complied with health rules, but the wedding exceeded New York State’s 50-person limit for social gatherings, officials said.

“This kind of blatant disregard for the well-being of others is not only extremely disappointing, it will not be tolerated,” Steven Bellone, the Suffolk County executive, said at a news conference. “If you violate the rules, you’ll be caught and held responsible.”

Ninety-one people attended the wedding, on Oct. 17, officials said. Thirty people — 27 guests, two employees and an outside vendor — later tested positive for the virus, and 156 people wound up in quarantine, officials said.

Mr. Bellone said the venue where the wedding was held, the North Fork Country Club in Cutchogue, would be fined $17,000. And a spokesman for the State Liquor Authority said it had opened an investigation into the matter “upon learning of this allegedly illegal and dangerous event.”

Raluca Pintea, the country club’s general manager, did not respond to requests for comment.

Although the birthday party, which took place in Bellport on Oct. 17, adhered to state restrictions on attendance, inadequate social distancing resulted in 26 guests testing positive and 132 people having to quarantine, officials said.

Mr. Bellone said it was important for county residents to consider the potential harm that even seemingly modest family gatherings could do. “These kinds of superspreader events are a threat to our public health and to our continued economic recovery,” he said.

These were not the first superspreader events in Suffolk County this fall. In September, dozens of people tested positive after a Sweet 16 party that the authorities said violated state restrictions.