Over 110 flights were affected at the Delhi airport after dense fog shrouded north India on Wednesday morning as visibility dropped to just 25 metres, disrupting the movement of traffic. The weather office issued a red alert over "very dense fog" in the national capital as cold wave conditions continued. As many as 25 trains headed to Delhi are delayed, Northern railways said. As roads remained engulfed in fog, several collisions were reported across Uttar Pradesh. One person was killed and 12 others injured after multiple vehicles collided on the Agra-Lucknow Expressway. In Bareilly, a speeding truck rammed into a house near the Bareilly-Sultanpur highway.