JERUSALEM - Israel's prime minister warned today that the kidnapping of three teenage yeshiva students in the West Bank, including one who is an American citizen, "will have grave consequences."

Prime Minister Benjamin Netanyahu accuses the Palestinian militant group Hamas of being behind Thursday's abduction, adding that, "We are in the middle of a complex operation. We need to be prepared for the fact that it may take more time."

"It is a serious incident and will have grave consequences," Netanyahu added.

Hamas, considered a terrorist organization by Israel and the U.S. State Department, has denied any involvement in the kidnapping. An Hamas spokesman has called Netanyahu's accusations "stupid comments."

The teens are Gilad Shaer and Naftali Frenkel, both 16, and Eyal Yifrach, 19. They were taken Thursday night while hitch-hiking on a main West Bank highway. Frenkel is also a American citizen, though he doesn't appear to have ever lived in the U.S. and the State Department has yet to recognize that he's American.

Seconds after being taken, one of the teens managed to call Israel's emergency line, whispering "We've been kidnapped," according to Israel's Channel 10. The police initially dismissed the call as a prank. It was hours later, around 3 a.m., that one of the boys' fathers reported his son missing and the police launched the search.

Earlier today, Netanyahu spoke with Palestinian President Mahmoud Abbas by telephone, telling him that he expected assistance in finding the teens. It was their first conversation in more than a year, coming two months after peace talks between the Israelis and Palestinians broke down.

"The Hamas kidnappers come from territory under Palestinian Authority control and returned to territory under Palestinian Authority control," Netanyahu told Abbas, according to a statement released by Netanyahu's office. "This incident exposes the true face of the terrorism that we are fighting against." Abbas' office has condemned the kidnapping.

Sources closed Palestinian Authority told ABC News they believe the teenagers were taken by a splinter Hamas group that is frustrated with the direction of Hamas. Hamas has recently formed a united government with the Palestinian Authority.

There have been no claims of responsibility offering evidence of the teens' abduction.

Over the past three nights, the Israeli military has arrested more than 150 Palestinians in the West Bank, most of them members of Hamas. The deployment in the West Bank is one of Israel's biggest since the end of the Second Intifada in 2002. On Sunday night, a 20 year-old Palestinian in the Jalazun refugee camp was killed in a raid. An Israeli Defense Forces spokeswoman told ABC News violence broke out during the raid after Palestinians started throwing rocks off rooftops and the soldiers responded with live ammunition.

After Netanyahu made his televised statement today, the head of the Israel Defense Forces, Lt. Gen. Benny Gantz, said: "This abduction will not pass without Hamas paying a big price." The Israeli government is reportedly considering deporting the Hamas members to the Gaza Strip, destroying Hamas operatives' homes and imposing sanctions on Hamas prisoners in Israeli prisons.

U.S. officials from the embassy in Tel Aviv have visited with Frenkel's family, according to Israeli media. Calls to Frenkel's family went unanswered and the embassy declined to comment. A statement by Secretary of State John Kerry condemned the kidnapping of the Israeli teens, adding, "many indications point to Hamas' involvement."

"We hope for their quick and safe return home," Kerry said. "We continue to offer our full support for Israel in its search for the missing teens, and we have encouraged full cooperation between the Israeli and Palestinian security services."

ABC News' Bruno Nota and Nasser Atta contributed to this report

Israeli Prime Minister Benjamin Netanyahu arrives to deliver a statement at the Israeli Defense forces headquarters on June 16, 2014 in Jerusalem. Thomas Coex/AFP/Getty Images