Security has been beefed up across the national capital after police received intelligence inputs on a possible terror strike, a senior police official said on Thursday. Airports across north India have been placed on high alert and security has been enhanced, say officials. Raids are being conducted by the Special Cell of Delhi Police at several locations across the city since Wednesday evening after the intelligence inputs suggested that three to four members of a terror outfit may have infiltrated into the city, he said. Four terrorists of the Pakistan-based JeM have entered Delhi and are planning to strike during