NAIROBI, Kenya — Extremists launched a deadly attack on a luxury hotel in Kenya’s capital Tuesday, sending people fleeing in panic as explosions and heavy gunfire reverberated through the complex. A witness said he saw five bodies at the hotel entrance alone. Al-Shabab — the Somalia-based Islamic extremist group that carried out the 2013 Westgate Mall attack in Nairobi that left 67 people dead — claimed responsibility. “It is terrible.