OMAGH, Northern Ireland (Reuters) - The people of Omagh offered a ``valley of tears'' Sunday for the first anniversary of Northern Ireland's deadliest bombing, their act of remembrance coming just hours after fresh street violence in the province.

Thousands of people filled Omagh's main street where one year ago a car bomb killed 29 people and injured more than 300 others.

The subdued mood on the streets of Omagh as townsfolk remembered the dead contrasted sharply with the previous night of petrol-bombing, looting and missile-throwing in nearby Londonderry, Northern Ireland's second largest city.

Music, prayer and flowers set the tone for mourners at the main outdoor service in this little market town about 75 km (45 miles) west of the provincial capital Belfast.

A lament on traditional Irish pipes filled the air in the moments before 3:10 p.m. (1410 GMT), the exact time the bomb exploded on August 15, 1998.

Only the sound of weeping broke the one minute of silence that followed.

Omagh's loss in Northern Ireland's 30-year conflict, which has claimed 3,600 lives, came just four months after a landmark peace deal was signed at Easter last year.

The attack, the work of defectors from the Irish Republican Army who oppose its two-year-old cease-fire, has been called ''the young people's bomb'' as nearly half its victims were under 20.

Blessings were said and sung in English, Irish and also in Spanish, a tribute to a 12-year-old boy and his teacher from Madrid who were killed in the blast.

An organ played J.S. Bach's ``Adagio in A minor'' as clergymen paid tribute to the ``happy children,'' ``devoted husbands,'' and ``loving mothers'' who were killed by the bomb.

They also prayed ``for the unborn little ones who we never saw.''

One of the victims, Avril Monaghan, would have given birth to twins a month later had she not been killed by the blast.

British Secretary of State for Northern Ireland Mo Mowlam and a Nobel peace prize winner, the moderate Catholic leader John Hume, joined the outdoor service, heads bowed in silence.

``No tears shall be lost, no tears forgotten, no tears shall have fallen in vain,'' a priest said before women poured water into a font in a ``valley of tears'' for the victims of armed Catholic- and Protestant-backed groups at odds over British rule.

They included the mothers of a ``disappeared'' IRA victim, the last British soldier killed in the conflict and a young Catholic man shot dead with his Protestant best friend in an attack on a bar by Protestant extremists.

The quiet dignity of Omagh's service could hardly have been more different from the atmosphere overnight in Londonderry.

Shops and vehicles were wrecked and three banks set on fire by Catholic youths angered by a massive Protestant parade Saturday.

Groups of masked teenagers hurled petrol bombs to vent their anger over the march by 10,000 ``Apprentice Boys'' marking a 17th century siege and victories against Irish Catholics.

The violence, also fuelled by police breaking up a sit-down protest by people trying to block another Protestant parade in Belfast, was condemned by representatives of the entire community.

``Violence at any time is unacceptable but to see violent attacks on the weekend when we are remembering the terrible atrocity at Omagh of just a year ago is doubly deplorable,'' Northern Ireland's security minister, Adam Ingram, said.

Most people in the province hope a stalemate in implementing the Good Friday peace accord can be ended by U.S. mediator George Mitchell when he returns to the province to chair new talks next month.

Protestant politicians have refused to share power with Sinn Fein, the IRA's political ally, until the IRA disarms, a move neither it not its Protestant foes show any sign of making.