Everyone washes their hands, similar to the “washing of hands” that is  done before eating bread.
A berachah is not said.
No speaking is permitted until after eating karpas.

Urehatz –  ורחץ
If Berachah is Mistakenly Recited

A. If one accidentally began to recite a berachah and realizes his mistake after reciting Baruch Atah Hashem, he must complete the berachah with the words “Lamdenie Hukecha” so as not to transgress the prohibition of a berachah l’vatalah, making a blessing in vain. 

B. If he already said Baruch Atah Hashem Elokeinu,  he must recite “Baruch Shem K’vod Malchuto L’olam Va’ed”. 

C. However, once he completed the entire berachah, he should be careful to keep his hands pure and clean if it is possible and during Rohtzah, when we wash for the matzah, he should wash without a berachah.  If, however, this is difficult for him, he should wash for Rohtzah and recite a berachah.