Haitians paused Sunday to remember the tens of thousands of people who died in a catastrophic earthquake four years ago, holding somber low-key commemorations on a national day of reflection.

President Michel Martelly and first lady Sophia Martelly placed a bouquet of white flowers at a potter's field north of the capital of Port-au-Prince that is being turned into an official memorial for those killed.

The pair observed a minute of silence facing a plaque placed at a large piece of rubble, with the inscription: "Jan. 12, 2010. We will never forget you."

Martelly said much had been accomplished since the disaster.

"Four years later, I think we have moved forward tremendously," Martelly told The Associated Press, noting a decline in the number of people still without housing, the number of hotels being built and regular visits from foreign leaders. "Of course, a lot remains to be done."

The 7.0-magnitude earthquake struck outside Haiti's capital on Jan. 12, 2010, and thousands of buildings toppled in Port-au-Prince and surrounding cities. Officials say more than 300,000 died, but no one knows for certain how many people lost their lives.

An estimated 1.5 million people were left living in gloomy tent camps that became symbols of the devastation and desperation heaped upon this already deeply poor nation. The number of displaced people has since fallen to 146,000 in a decline attributed to a combination of voluntary departures, rental subsidies and violent evictions.

Haiti Quake Anniversary

Relatives place crosses, in remembrance of those family members who died in the 2010 earthquake. (Jean Marc Herve Abelard/Associated Press)

The day in the capital began like any other Sunday with churchgoers dressed in their best skirts and slacks wending their way through streets noticeably clear of the rubble that clogged them long after the quake.

Haiti's radio and television stations played somber programs and music. Martelly's government declared a day of remembrance and reflection, with the Haitian flag flown at half-staff and clubs ordered closed.

"We need this, we need to remember our family members and friends who died," Peterson Lebours said as he visited a memorial at the national cemetery, which was a dumping ground for bodies after the quake. The 35-year-old teacher lost a cousin, several friends and co-workers.

The precarious existence for those still living in the settlements was underscored as people scavenged through the charred remains of a camp that caught fire Saturday and killed four people, including three children. Camp dwellers wouldn't say if the blaze was an arson attack aimed at expelling them, as many such fires are.

"I'm shaken up, clearly bothered, but I've turned everything over to God," said Gary Leon, a 36-year-old security guard whose 3-year-old daughter, Sabine, died from her burns. "I was very close to her. She took off my shoes at night. I'm beginning to miss her."

While many Haitians were remembering loved ones lost in the quake, activists used the occasion to criticize the reconstruction effort while non-governmental groups promoted their own work.

The foundation of former President Bill Clinton, the onetime UN special envoy to Haiti, sought to cast the day in a positive light.

"As we remember this solemn anniversary, we also recognize that Haiti has the opportunity for a bright and prosperous future, one that its people and children deeply deserve," it said in a statement.