Terminal at London's Heathrow Airport reopens after possible hazardous substance investigation

LONDON — Part of a terminal temporarily closed at London's Heathrow Airport was reopened later Monday when police reported finding no sign of a hazardous substance blamed for harming about 20 people, authorities said.

The Metropolitan police said the patients treated at Terminal 4 were not seriously injured and that officers found no trace of any dangerous material.

The departures area of the terminal at the U.K.’s busiest airport was evacuated and closed as a precaution for about three hours as police, firefighters and ambulance crews responded.

Crowds of passengers with luggage crowded outside the terminal in the late afternoon. As the sun went down, some wrapped themselves in space blankets to keep warm.

The arrivals area of the terminal remained open throughout and all other terminals were operating.

The airport apologized for the disruption and said it was working to make sure all departures took off as planned.