According to a news report from Taiwanese news network Liberty Times Network (LTN), a fire broke out this morning in the Heping Basketball Gymnasium this morning.
Reddit user S890127 provided a translation of the article describing the cause of the incident. According to LTN, two generators were running without stop for 48 hours straight in preparation for the Mid-Season Invitational. Oil tanks from the generators burned down and leaked, agitating the flames.
No one was harmed in the fire and there were no significant damages to other equipment or the venue itself. There are no reports on whether the generators overheated due to the negligence of an individual or defectiveness, or if this was an isolated incident.
Riot has yet to release a statement detailing any plans to postpone the Semifinals on May 17-18.