Police in southern California are investigating the circumstances that led to the hospitalization of nearly 30 runners who participated in the Santa Barbara Half on Sunday.

Santa Barbara police said in a statement to the Associated Press that they had opened an investigation after receiving reports from Santa Barbara Cottage Hospital about multiple half-marathon participants seeking medical treatment for “unusual symptoms”.

Cottage Health said in a statement it had a “larger than expected number of emergency visits … a number of them with similar symptoms of undetermined cause”.

Race organizers say they believe any illness is attributable to heat or dehydration. The high on the day of the race was 88F (31.1C), an unusually high temperature for this time of year.

Neither the hospital nor police have detailed the symptoms beyond calling them unusual.…