A Palestinian has stabbed an Israeli teenager to death in her bedroom in the West Bank before he was shot dead, the Israeli army and a Jerusalem hospital said.
The victim was Hallel Yaffa Ariel, 13, according to a spokeswoman for Jerusalem's Shaarei Zedek hospital.
The military said an Israeli civilian security officer who arrived on the scene was also stabbed. He is in a serious condition, emergency services spokesman Yonatan Yagodovsky said.
Over the last nine months, Palestinians have carried out dozens of attacks that have killed 33 Israelis and two Americans. About 200 Palestinians have been killed during that time, most identified as attackers by Israel.
The assaults were once near daily occurrences but have become less frequent in recent weeks. In June, however, Palestinian gunmen killed four Israeli civilians in Tel Aviv.
Kiryat Arba is near the city of Hebron, which has been a flashpoint of violence in the recent wave of attacks. About 850 Israelis live there in heavily fortified enclaves amid 200,000 Palestinians.
Meanwhile, five Palestinians, including two police officers, were killed in two overnight shootings.
Police spokesman Loaie Izrekat said 16 others were injured in the shootings. The incidents underscore a lack of gun control in the West Bank.
Mr Irzekat said a Palestinian gunman attacked the home of a police officer in the town of Nablus. When officers arrived to investigate, they came under fire and two were killed.
Three more Palestinians were killed in a shootout between two clans sparked by an argument over a wedding hall in the town of Yaabad in the northern West Bank. Police imposed a curfew on the town overnight.
Palestinian police have struggled to crack down on widespread illegal gun possession in the West Bank.
The Palestinian health ministry identified the assailant as Mohammed Tarayreh, 19, from nearby Bani Naim.