A vigil will be held in Nashville on Wednesday to grieve the three children and three adults shot to death this week at a Christian elementary school, as Tennessee's governor revealed that his wife was close friends with the two educators killed in the attack.

The ceremony will commemorate the three 9-year-old students, the school's head, a substitute teacher and a custodian killed in Monday's shooting. It will take place at a public park in the heart of the city, the Tennessee state capital.

Over the past two days, mourners have left flowers, balloons and stuffed teddy bears at the gate of the Covenant School, where the attack unfolded on Monday.

Six white crosses were placed nearby, each adorned with a blue heart, the name of one of the victims and a Bible verse: "Blessed are those who mourn, for they shall be comforted."

The shooting, the latest of dozens carried out at U.S. schools this year alone, has touched a particularly raw nerve, in part because three victims were so young and in part because it scorched Nashville's tight-knit Christian community.

"Many Tennesseans are feeling the exact same way: The emptiness, the lack of understanding, the desperate desire for answers, the desperate need for hope," said Tennessee Governor Bill Lee in a video posted on his Twitter feed.

The governor's wife Maria, substitute teacher Cynthia Peak and the head of the school Katherine Koonce previously taught together at another school, he said. All three remained close friends for decades. Peak and the governor's wife had planned to have dinner together on Monday, he said.

"I understand there is pain. I understand the desperation to have answers, to place blame, to argue about a solution that could prevent this horrible tragedy," he said. "This is not a time for hate or rage."

The three children killed were Evelyn Dieckhaus, William Kinney and Hallie Scruggs, whose father is head pastor of Covenant Presbyterian Church, which is affiliated with the school. In addition to Koonce, 60, and Peak, 61, custodian Mike Hill, 61, was killed in the attack.

The assailant, Audrey Elizabeth Hale, 28, went to the grade school armed with two assault-style weapons and a handgun, police said.

The guns were among seven firearms Hale had legally purchased in recent years from five Nashville-area stores, Metropolitan Nashville Police Chief John Drake told reporters on Tuesday.

The attack has added fuel to a long-running national debate over gun ownership rights and regulations. Tennessee has some of the most lax gun laws in the nation. The state does not require a permit to carry a firearm, regardless of whether it is concealed or openly carried.