Seven persons, including four sanitation workers, died due to asphyxiation on Saturday while cleaning sewer of a hotel in Gujarat’s Vadodara district, officials said. The incident happened at a hotel in Fartikui village in Dabhoi tehsil, about 30 km from Vadodara city.Three employees of the hotel were also among those killed. “When one sanitation worker failed to come out of the manhole, others went inside. All of them died due to asphyxiation,” district collector Kiran Zaveri.