Nearly 30 runners fall ill at half-marathon as police investigate the cause

Nearly 30 runners who took part in a half-marathon in Santa Barbara, California, in the United States have been taken to hospital after falling ill. They developed 'unusual symptoms' after the Santa Barbara Half Marathon, held on Sunday.

Santa Barbara police said they had opened an investigation after receiving reports from Santa Barbara Cottage Hospital about multiple participants seeking medical treatment.

Cottage Health said in a statement it had seen a larger than expected number of emergency visits, with a number of patients showing similar symptoms of undetermined cause.

By Monday, 27 participants had come to emergency rooms in Santa Barbara and Goleta, a small city about 10 miles west of Santa Barbara.

Of those, 24 patients had been treated and discharged as of Monday morning. The three others were in stable condition, the company told the Associated Press.

Race organisers 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.

More than 4,640 people competed in the half-marathon, which spanned about 13 miles, according to the organisers' website.

Event director David Monico said organisers transported 15 people from the medical tent to local hospitals. He said the event's medical team treated numerous runners for dehydration and overheating both on the course and at the finish line.

Monico told the Guardian that organisers have 'no additional information to suggest that the issues some of the participants experienced were caused by anything other than endurance event exertion-related symptoms'.

Police said they are examining the circumstances of the incident on the basis of the hospital's reports.