Yes, it is possible.
Flash Discharge and ground currents are both means by which an indirect strike by lightning can cause injury.
Additionally, strikes that directly hit multiple people, while rare, apparently are not unheard of (emphasis mine):
> In the contest between people and lightning, lightning wins. **Although lightning rarely strikes more than one person at a time** , over the course of a year the damages, deaths and injuries add up to make lightning a serious threat. By studying the outcome of human-lightning encounters, scientists hope to find more ways to prevent such meetings from occurring in the first place.
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