Cases in which lightning causes multiple fatalities can occur when lightning either strikes the ground or an object on the ground, such as a tree. The energy from that lightning strike radiates outward along the ground.
Therefore, anyone in the immediate vicinity of that lightning strike may be killed or injured by the lightning, according to National Weather Service (NWS) Lightning Safety Specialist John Jensenius.
"It's not all that frequent in the United States. However, in Africa, it's actually quite common because many areas don't have adequate protection," Jensenius said.
Lightning strikes are frequent across Rwanda. The country's police record a number of human and livestock deaths each year.
The number of fatalities in the recent Rwanda incident was unusual but not unprecedented, according to Jensenius.
In June 2011, a lightning strike killed 19 children at a school in Uganda, according to Mail & Guardian.
"Children were on a dirt floor and the lightning spread across the floor. It killed a number of children and also the teacher," Jensenius said.
In the U.S., events of this nature are less common because the homes and buildings have wiring and plumbing in them. Therefore, if lightning strikes a home or a building, it will follow the wiring or plumbing to the ground, according to Jensenius.
"In Uganda and some of the other African countries, many people live in huts or homes that don't have any wiring or plumbing. So if lightning strikes those homes, it doesn't have a path to follow to the ground," Jensenius said.
While these events are rare in the U.S., there is a possibility of it happening if proper lightning safety precautions are not followed. For example, in events where people gather in unsafe structures, such as in an outdoor tent for a wedding or a reunion.
"There is a possibility that if lightning were to strike the tent or nearby, there could be a large number of people killed or seriously injured by a lightning strike," Jensenius said.
While it is a concern in the U.S., the likelihood of that happening is rare because there are often safe buildings nearby so most people are inside where it is safe.
"If you're outside at some kind of outdoor event, just simply go in your car and stay there for at least 30 minutes after the last clasp of thunder," Jensenius said.
The best way to avoid these deadly events is to go inside a substantial, safe building during a storm.
EDITOR’S NOTE: Amanda Schmidt is a staff writer for AccuWeather.com.