Ismail Haniyeh, a top leader of Hamas, was assassinated on Wednesday by an explosive device covertly smuggled into the Tehran guesthouse where he was staying, according to seven Middle Eastern officials, including two Iranians, and an American official.

The bomb had been hidden approximately two months ago in the guesthouse, according to five of the Middle Eastern officials. The guesthouse is run and protected by the Islamic Revolutionary Guards Corps and is part of a large compound, known as Neshat, in an upscale neighborhood of northern Tehran.

Mr. Haniyeh was in Iran’s capital for the presidential inauguration. The bomb was detonated remotely, the five officials said, once it was confirmed that he was inside his room at the guesthouse. The blast also killed a bodyguard.

The explosion shook the building, shattered some windows and caused the partial collapse of an exterior wall, according to the two Iranian officials, members of the Revolutionary Guards briefed on the incident. Such damage was also evident in a photograph of the building shared with The New York Times.

Mr. Haniyeh, who had led Hamas’s political office in Qatar, had stayed at the guesthouse several times when visiting Tehran, according to the Middle Eastern officials. All of the officials spoke on the condition of anonymity to share sensitive details about the assassination.