By Rob Picheta, CNN
Polish police said that a total of seven officers were injured in clashes on Tuesday at the country's border with Belarus.
They include a male officer who was hit in the head with a stone, and a female officer who was taken to hospital due to a head injury.
Five more had injuries to their arms and legs, the police wrote on Twitter.
The Belarusian border agency has told CNN's Matthew Chance that some migrants are now being moved to a processing centre nearly one mile from the border with Poland.
Video filmed by CNN shows a small group with young children walking away from the official border checkpoint where earlier violence erupted.
Officials told CNN people can decide if they want to be taken to be processed, given shelter and medical attention.
Officials also told CNN a decision will be made on whether to deport them
From CNN's Matthew Chance in Poland
Belarusian state border committee officials have told CNN that a logistical center is being set up indoors on the Belarusian side of the Poland-Belarus border for some of the most vulnerable migrants.
The official added that the process of splitting up these refugees was underway and that some would be sent to the logistical center which is a short distance from the border, where violent clashes broke out and temperatures have been freezing.
Some background: Belarus is launching an investigation into what it calls the “incident” at the Belarus-Polish border earlier Tuesday, the official representative of the State Border Committee, Anton Bychkovsky, told Belarus state media outlet BelTA. Violence erupted as migrants threw stones at Polish border guards who responded with tear gas and water cannon.
You can read more about the situation at the border here.
From CNN's Antonia Mortensen near the Polish-Belarus border
A Polish border guard was hit by a stone and injured during skirmishes on the country's boundary with Belarus on Tuesday, Poland's border force has said.
The female guard is receiving medical attention after the incident, they added.
Earlier, Polish police tweeted that an officer had separately been injured after being hit with a projectile.
“Unfortunately - as a result of an attack by people inspired by the Belarusian side, one of the policemen was seriously injured,” the police tweeted.
From CNN's Nina Avramova
Belarusian President Alexander Lukashenko is using migrants along the country’s border with Poland, Lithuania and Latvia as a “hybrid tactic” against other countries, NATO’s Secretary General said on Tuesday.
Jens Stoltenberg said the alliance is "deeply concerned about the way the Lukashenko regime is using vulnerable migrants as a hybrid tactic against other countries, and this is actually putting the life of the migrants at risk.”
He was speaking ahead of a meeting with EU defense ministers on Tuesday, during which the worsening situation on the Poland-Belarus border is set to be discussed.
From CNN's Katharina Krebs in Moscow
Belarus is launching an investigation into what it calls the “incident” at the Belarus-Polish border earlier Tuesday, the official representative of the State Border Committee, Anton Bychkovsky, told Belarus state media outlet BelTA. Violence erupted as migrants threw stones at Polish border guards who responded with tear gas and water cannon.
Bychkovsky said the flare-up was instigated by the Polish side and accused them of "violent actions" against migrants on the border.
"In fact, the fence is on Polish territory, so Belarusian border guards have no legal right to approach it. To push back the migrants, the Polish side used tear gas," Bychkovsky said.
"This angered the refugees even more, who began throwing stones, sticks, everything that came to hand at a critical moment, including shoes, at the security forces. In response, the Polish side fired water cannon jets and stun grenades at the unarmed refugees."
Belarus authorities recorded the use of special equipment by the Polish security forces against unarmed people on the Belarusian side, he said.
“This is regarded as nothing other than violent actions against persons who are on the territory of another country. The Belarusian side is initiating an investigation of this incident,” Bychkovsky announced.
See what Belarus-Poland border looks like after violence erupted:
Migrants are stranded in freezing conditions at the Poland-Belarus and “there is very little sign at this point of any side backing down,” CNN’s Matthew Chance reported on Tuesday from the site.
The crowds were sprayed with water cannon after tensions escalated with Polish forces on Tuesday morning. “There was something acrid in the water” that stung people’s eyes and made others cough, Chance reported from within the crowds.
He said temperatures drop to “well below freezing at night” and can plunge dangerously low in Belarus in the depths of winter.
“This humanitarian crisis is running against the clock of the seasons … we really are going to have an acutely serious situation” if temperatures fall in the coming days and weeks, he said.
People are without sufficient shelter — most only have access to a tent or a sleeping bag, and a few clothes, as the crisis drags on.
“Everybody’s wet, everybody’s hungry,” Chance said, summarising the sentiment among many of the migrants gathered at the site.
From CNN's Katharina Krebs in Moscow
Belarus' President Alexander Lukashenko said he has spoken with Angela Merkel about the migrant crisis at the Polish border, and will hold another call with the German Chancellor soon.
The President's Office said in a statement that Lukashenko made a proposal on how to deal with the situation, and that the two leaders would speak again once Merkel had raised the issue with EU member states.
"There are more than 2,100 (migrants) and maybe even more, who are concentrated at the Bruzgi border crossing. You know that they have set up camp there, 800 meters from this crossing, and were constantly there for a week. Yesterday they took off and walked 800 meters and filled up the Bruzgi border crossing. This is the biggest problem," Alexander Lukashenko told the German chancellor, according to the readout.
"I know that there have already been attempts to deliver weapons to the migrant camp. As well as provocations that can lead to a violent conflict. In no case should this be allowed. This so-called problem cannot become the unleashing of a heated confrontation," he said.
From CNN's Antonia Mortensen near the Polish-Belarus border
Polish police said an officer guarding the border with Belarus was seriously injured after being hit by a projectile.
“Unfortunately - as a result of an attack by people inspired by the Belarusian side, one of the policemen was seriously injured,” the police tweets.
