US troops have detained more than a dozen Iraqis suspected of attacks on coalition forces, in a raid on the hometown of Saddam Hussein.
Tikrit has proved difficult to quell
Hundreds of soldiers poured into Tikrit just before midnight in one of the biggest raids since the end of the war.
However, no arms caches were reported found and troops failed to catch five of the 18 people on their wanted list.
Hours later, a Baghdad hotel used by foreign nationals was hit by rocket fire, but no-one was hurt, staff said.
At least two rocket-propelled grenades hit the first and fourth floors of the Burj al-Hayat, according to staff.
It came a day after two US military flights came under suspected hostile fire, with nine soldiers killed when one of the flights crashed in the flashpoint town of Falluja.
The head of Iraq's Governing Council, meanwhile, has told the BBC thousands of Iraqis detained by coalition forces since the start of the war could soon be freed.
The raid in Tikrit lasted five hours and was the third carried out by the Fourth Infantry Division since June.
"It was a good night," said Lieutenant Colonel Steven Russell. "Tikrit will be a safer place tomorrow as a result."
The troops found fake police identity cards, computer equipment used to make the cards and evidence of bomb-making equipment, Colonel Russell said.
The swoop came on a day when the US military freed 60 Iraqis from Abu Ghraib prison near Baghdad, in a move to ease resentment against the occupation forces.
Speaking to the BBC on Friday, the head of the Governing Council, Adnan Pachachi, said more Iraqi prisoners are expected to be freed.
"There should be released several hundreds, perhaps thousands, in the next few months," he said.
The US soldiers died when the Black Hawk helicopter they were travelling in came down in Falluja, 50 kilometres (30 miles) west of Baghdad.
A witness told the Associated Press he had heard the whoosh of a rocket and saw it hit the helicopter's tail.
US HELICOPTER CRASHES IN IRAQ
2 Jan - OH-58 Delta Kiowa Warrior shot down near Falluja - one soldier killed
15 Nov - Two Black Hawks crash in Mosul, at least 17 killed
7 Nov - Black Hawk shot down near Tikrit, six killed
2 Nov - Chinook shot down near Falluja, killing 16 US soldiers
25 Oct - Black Hawk crashes near Tikrit, reportedly hit by ground fire - soldier injured
The US military said it was investigating the cause.
Falluja lies in the so-called "Sunni triangle" area, where support for Saddam Hussein remains strong and coalition forces have repeatedly come under attack.
Another aircraft, a C-5 transport plane with 63 people on board, was forced to return to Baghdad airport following takeoff after it was hit by hostile fire, the US air force said.
It said the type of weapon used in the attack had not been identified.
An unnamed official at the Pentagon had earlier said the plane had apparently been hit by a surface-to-air missile.