Church services are being held across Poland to start a week of mourning following the death of President Lech Kaczynski, who died along with 95 others when their plane crashed in Russia on Saturday.
Send us your comments.
IVONNA NOWICKA, WARSAW, POLAND
Ivonna plans to attend the funeral of the president
My first reaction was utter disbelief.
And when the scale of the catastrophe became clear I felt this urge, this wish, to turn time backwards and delete this event from the pages of our history.
Soon after the announcement people started to hang the Polish national flags with black ribbons on balconies as a symbol of mourning.
Lights have appeared all over the city and thousands of grief-stricken Poles rushed to the presidential palace to put lights there.
I myself was not fond of the policies of late President Kaczynski, but this doesn't matter at a moment like this. We Poles unite in grief and solidarity is felt everywhere.
In the beginning many people felt that the plane crash on Russian soil would worsen our difficult relations with Russia. But this has not happened - they are united with us in our grief.
In a strange turn of events, the crash seems to have brought both Polish and Russian politicians, as well as ordinary Poles and Russians, closer to each other.
There is a comment often repeated now that future political tensions will subside.
History has shown that Poles have the talent to unite in difficult times.
MACIEJ MARDYLLO, 34, WARSAW, POLAND
After news of the deaths spread people gathered by the Presidential Palace
I feel very sad. It is the biggest tragedy Poland has faced.
A lot of valuable people died in the place which is already considered one of the most tragic places in Polish history.
People in Poland are still in shock. On buses, on trams all over the place I have heard a lot of talk about what happened yesterday. Even in shopping malls people were just gathering and watch the TV, and all were in total silence.
From my point of view this moment is very tragic. But I think that maybe it will be the breaking point for our internal relationships in politics, and perhaps end the war between parties.
It might help relationships with Russia. We all appreciate what Prime Minister Putin has done and his support. It has been amazing.
Bronislaw Komorowski has a lot of responsibility now. He was elected as a candidate for president from his party, but now, in such tragic circumstances, he has to take responsibility as temporary president for the whole country.
KAMILA KASPRZAK, 24, WARSAW, POLAND
Kamila Kasprzak was in a Warsaw cafe when she heard the news
I was sitting in a cafe when I heard the news. It immediately spread via SMS.
Everybody was shocked. There was a big commotion in the cafe.
Things have calmed down now, but we are all still in a state of shock.
We are waiting for our prime minister to address the nation.
I never supported Kaczynski - he was very unpopular - and some unrefined comments may be heard on the streets today.
But nevertheless - he is our President. Nobody wanted this to happen to him.
People are suspicious about the nature of the accident. So many important officials were on that plane.
And of course we are preparing for presidential elections this year.
People are asking - why did this crash happen? I think it could cause a huge political argument.
We were already having difficult relations with Russia. They could be even more difficult now.
MONIKA SIDOR, 26, LONDON
Monika Sidor is concerned about future relations with Russia
I am shaking all over. I'm in shock. This news is so horrible.
My mother has just been on the phone from Poland - crying to me.
Even though she did not like Kaczynski, she would never wish this on him. And there were so many other passengers on that plane.
There were many familiar faces - faces we all know in Poland - so it feels very personal to us.
The president was from my town - Gdansk. So I did feel a connection to him, even though he was on the right and I am on the left.
I was in Poland yesterday - at the airport.
Then this morning I get a text from my friend telling me the president is dead. Since then, everyone I know has started calling me.
Will this affect our relations with Russia? That depends what we find out about the crash. There are many questions to be answered.
We hear reports that the plane tried four times to land. So what kind of advice did the Russian air traffic control give the pilots? It doesn't make sense. Remember, these are the best pilots in Poland.
It's a shame because things were improving between Poland and Russia. We haven't been very good friends so everyone was happy that the climate was changing.
Now suddenly, this happens and everything is horrible.
MACIEJ ZIAREK, 23, TORUN, POLAND
Maciej Ziarek is a student in Torun, in the North of Poland
I worked late, so when the phone rang I was still sleeping. My mom told me about it - I couldn't believe it. This is a horrible situation. They wanted to be there, to pay homage, to pay tribute to officers who were murdered seventy years ago, and now they died too.
I live with two other students. None of us could believe what happened. It is a real shock for the citizens of Poland to lose the president, the first lady and so many more government people.
We are waiting for a full list of victims and information about why this tragedy happened. Nobody wants this to be true, and everyone will remember this day.
IWONA ROMAN, 30, STOCKHOLM, SWEDEN
Iwona Roman says the death has made her feel closer to her country
I read the news of the Polish president's death this morning. I have been living abroad for many years of my life now, but the news was shocking nevertheless.
Although I have never been a fan of the Kaczynski brothers' right-wing politics, the news of Lech Kaczynski's death touched me in ways unforeseen. I was really shocked and lived through this news as though someone close to me died.
Patriotism displays its face in surprising moments, and the moment I heard of Mr Kaczynski's death it exacerbated a sensation of closeness I haven't felt for my country for many years, or perhaps never. Although I found this feeling odd, it was also strangely warm - a feeling of unity with all the people in Poland, my country.
I think in light of this event, politics aside, the country will mourn a human tragedy which, along with the Katyn massacre, will be something we the Polish people never forget.