diff --git a/scripts/sync.sh b/scripts/sync.sh
index 345a7f5..0c42062 100755
--- a/scripts/sync.sh
+++ b/scripts/sync.sh
@@ -105,6 +105,19 @@ if [ -n "${MODE}" ]; then
         rm "${EXPLORER_PATH}/tmp/index.pid"
       fi
     fi
+    # Check if the script is already running (tmp/db_index.pid file already exists)
+    if [ -f "${EXPLORER_PATH}/tmp/db_index.pid" ]; then
+      # The tmp/db_index.pid file exists. Check if the process is actually still running
+      ps -p `cat ${EXPLORER_PATH}/tmp/db_index.pid` > /dev/null
+      if [ $? -eq 0 ]; then
+        # Script is running so the data is locked and we must exit now and try again later
+        echo "Script already running.."
+        exit 1
+      else
+        # Script is not actually running so we can delete the lock file
+        rm "${EXPLORER_PATH}/tmp/db_index.pid"
+      fi
+    fi
   fi
   # Check if the node path was specified
   if [ -z "${NODE_PATH}" ]; then