NEW DELHI, June 25 (Xinhua) -- At least four people were killed and three others injured in an explosion at a scrap shop in the northern Indian state of Uttar Pradesh Monday, police said.

The incident took place in the Civil Lines area of the state's Muzaffarnagar district.

"A device exploded at the scrap dealer's shop this morning. Apart from the scrap dealer, three passersby died in the explosion, while three others sustained injuries," a police official said.

The injured had been admitted to a government hospital where the condition of two were said to be serious, he said.

A probe had been launched to ascertain the cause of the explosion, the official added.