Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.

Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.

Post-it note with handwritten message in red marker. The message reads: "We will love you forever." Creasing due to exposure to the elements at the Wilkins memorial.

Folded card on blue paper with hand drawn illustrations and assorted stickers featuring various animals and other items, including owls, paw prints, lady bugs, bears, a fish, flower, cat, and the Disney character, Tinkerbell.

Card from a student at West Allegheny Middle School in Imperial, Pa. The front features a hand-colored illustration of a turtle with floral and geometric motifs on its back, legs, and neck. The back contains a handwritten note and a sticker with blue text reading: "Stronger Together." The stock signature: "From your friends at West Allegheny Middle School" appears in the lower center.

Handmade, screen-printed card on pink paper with green paint. An abstract shape, perhaps meant to evoke a broken heart, appears in the center. Signed, lower right: "Love, Brian S." The card has been laminated.

Note from a member of The Church at Severn Run in Severn, Maryland. The note reads: "In light of recent events, I want to send over my condolences and love. I want you to know that this is not who we Christians are. We are not hate- only love. Your community is always and forever in prayers. [Smiley face]."

Note from a member of The Church at Severn Run in Severn, Maryland. The note is enclosed in an envelope with church letterhead, reading: "The Church at Severn Run: Love Well, Live Jesus, Believe Big!" The letter is dated Oct. 28, 2018 and contains words of condolence and prayer. The church's contact information is included on the back of the envelope.

Card from a student at West Allegheny Middle School in Imperial, Pa. The front features a hand-colored illustration of a leaf with geometric motifs and the signature, "Ty" [last name redacted]. The back contains a handwritten note, a "Stronger Together" sticker, and the stock signature: "From your friends at West Allegheny Middle School."

Card from a student at West Allegheny Middle School in Imperial, Pa. The front features a hand-colored illustration a heart with geometric and floral motifs. The back contains a handwritten note, as well as the stock signature: "From your friends at West Allegheny Middle School."

Card with the words of the Prayer for Peace handwritten in blank ink on a purple note card on the front and back. The Prayer for Peace is an eighteenth century Chasidic Jewish prayer adopted by liberal Jewish denominations in North America. The note concludes: "In loving memory of Rose Mallinger."

Card with the words: "My heart is with Squirrel Hill" on the front cover. The message inside is from a life-long Pittsburgh resident with ties to Duquesne University, who writes: "I know that this is a city of incredible love and acceptance, which just makes this tragedy hurt even more."

Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.

Post-it note with handwritten message in blue marker. The message reads: "I pray to you and remember you always. May your soul rest in peace." Tape affixed on the upper center.

Post-it note with handwritten message in blue ink. The message reads: "I think about you constantly. Sending love." The Hebrew acronym, "with the help of heaven," appears in the upper right.

Letter from a member of the Point Loma Community Presbyterian Church in San Diego, California. The letter reads: "My thoughts and prayers are with you. Clara [last name redacted]."

Folded card with colored pencil illustration. Front and back of card feature Stars of David enclosed by hearts. Inside reads: "Thumbs up I feel your pain" and features a stylized thumbs up and a smiley face.

Card from the Friendship Circle of Illinois. On the left side, the card reads: "To the Jewish community of Pittsburgh sheyichyu (may they live), I will take upon myself to stay in shul (synagogue) at least for 3 aliyas (sections Torah reading where a congregant is called up to the reading podium). On the right side, the card contains cartoonish illustrations of a building and several figures. The acronym "B"SD" (with the help of heaven) appears on the upper right.

Card from a congregant at the Holy Angels Parish. The front cover contains a stock illustration of a haloed dove flying in front of Noah's ark. The inside reads: "Dear Tree of Life members, I'm sorry for all of the uncalled for events and all of the inconvenience of them. We hope you all feel better and don't worry but keep them in mind. Sincerely, Michaela [last name redacted] from Holy Angels CCD."

Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.