Sec. 8. Securing a Quorum. When a call of the house is moved for one of the above purposes and seconded by 15 members (of whom the speaker may be one) and ordered by a majority vote, the main entrance to the hall and all other doors leading out of the hall shall be locked and no member permitted to leave the house without the written permission of the speaker. The names of members present shall be recorded. All absentees for whom no sufficient excuse is made may, by order of a majority of those present, be sent for and arrested, wherever they may be found, by the sergeant-at-arms or an officer appointed by the sergeant-at-arms for that purpose, and their attendance shall be secured and retained. The house shall determine on what conditions they shall be discharged. Members who voluntarily appear shall, unless the house otherwise directs, be immediately admitted to the hall of the house and shall report their names to the clerk to be entered in the journal as present.

Source.

They're fleeing the state because otherwise they'll be arrested.