Two people were killed and another two injured in a mid-air collision Saturday involving a helicopter and a gyrocopter near Oshkosh, Wisconsin, officials said, while another two other people were killed in a separate incident in which a small plane crashed into a nearby lake.

A spokesperson for the Experimental Aircraft Association told CBS News in a statement that the mid-air collision occurred a little before 12:30 p.m. local time in the area of the Wittman Regional Airport.

The Winnebago County Sheriff's Department told the EAA that two people were killed and two injured in that collision, the spokesperson said.  

The National Transportation Safety Board informed the EAA that the aircraft belonged to individuals attending the EAA's annual fly-in convention in Oshkosh, but who were not involved in the air show, the spokesperson added.

The Federal Aviation Administration identified the aircraft as a Rotorway 162F helicopter and an ELA Eclipse 10 gyrocopter, with two people aboard each.

Separately, at about 9 a.m. Saturday, a small North American T-6 plane carrying two people crashed into Lake Winnebago near Oshkosh after departing Wittman Regional Airport, the FAA said. 

Both people aboard died, according to the sheriff's office. 

The FAA and the NTSB are investigating both incidents. The names of the victims in both crashes were not immediately released, and the exact circumstances of the crashes were unclear. 

In:
• Plane Crash
• Helicopter Crash
• Wisconsin