diff --git a/monasca_api/common/repositories/mysql/alarms_repository.py b/monasca_api/common/repositories/mysql/alarms_repository.py
index f35d0f540..40bdac716 100644
--- a/monasca_api/common/repositories/mysql/alarms_repository.py
+++ b/monasca_api/common/repositories/mysql/alarms_repository.py
@@ -12,7 +12,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from datetime import datetime
 from oslo_log import log
+from time import time
 
 from monasca_api.common.repositories import alarms_repository
 from monasca_api.common.repositories import exceptions
@@ -113,6 +115,8 @@ class AlarmsRepository(mysql_repository.MySQLRepository,
     def update_alarm(self, tenant_id, id, state, lifecycle_state, link):
 
         cnxn, cursor = self._get_cnxn_cursor_tuple()
+        time_ms = int(round(time() * 1000.0))
+        now = datetime.utcfromtimestamp(time_ms / 1000.0)
 
         with cnxn:
 
@@ -130,12 +134,13 @@ class AlarmsRepository(mysql_repository.MySQLRepository,
 
             prev_alarm = cursor.fetchone()
 
-            parms = [lifecycle_state, link]
-            set_str = "lifecycle_state = %s, link = %s, updated_at = NOW()"
+            parms = [lifecycle_state, link, now]
+            set_str = "lifecycle_state = %s, link = %s, updated_at = %s"
 
             if state != prev_alarm['state']:
                 parms.append(state)
-                set_str += ",state = %s, state_updated_at = NOW()"
+                parms.append(now)
+                set_str += ",state = %s, state_updated_at = %s"
 
             parms.extend([tenant_id, id])
 
@@ -155,7 +160,7 @@ class AlarmsRepository(mysql_repository.MySQLRepository,
 
             cursor.execute(update_query, parms)
 
-            return prev_alarm['state']
+            return prev_alarm['state'], time_ms
 
     @mysql_repository.mysql_try_catch_block
     def delete_alarm(self, tenant_id, id):
diff --git a/monasca_api/v2/reference/alarming.py b/monasca_api/v2/reference/alarming.py
index d4b0aa9e1..0720d6b57 100644
--- a/monasca_api/v2/reference/alarming.py
+++ b/monasca_api/v2/reference/alarming.py
@@ -44,8 +44,10 @@ class Alarming(object):
     def _send_alarm_transitioned_event(self, tenant_id, alarm_id,
                                        alarm_definition_row,
                                        alarm_metric_rows,
-                                       old_state, new_state):
+                                       old_state, new_state,
+                                       time_ms):
 
+        sub_alarms = []
         metrics = []
         alarm_transitioned_event_msg = {u'alarm-transitioned': {
             u'tenantId': tenant_id,
@@ -58,9 +60,13 @@ class Alarming(object):
             u'severity': alarm_definition_row['severity'],
             u'oldState': old_state,
             u'newState': new_state,
+            u'timestamp': time_ms,
+            u'subAlarms': sub_alarms,
             u'metrics': metrics}
         }
 
+        # TODO(msbielinski): need to populate subalarms
+
         for alarm_metric_row in alarm_metric_rows:
             metric = self._build_metric(alarm_metric_row)
             metrics.append(metric)
diff --git a/monasca_api/v2/reference/alarms.py b/monasca_api/v2/reference/alarms.py
index 6ff0dce5c..d5b60afbc 100644
--- a/monasca_api/v2/reference/alarms.py
+++ b/monasca_api/v2/reference/alarms.py
@@ -142,9 +142,9 @@ class Alarms(alarms_api_v2.AlarmsV2API,
         alarm_metric_rows = self._alarms_repo.get_alarm_metrics(alarm_id)
         sub_alarm_rows = self._alarms_repo.get_sub_alarms(tenant_id, alarm_id)
 
-        old_state = self._alarms_repo.update_alarm(tenant_id, alarm_id,
-                                                   new_state,
-                                                   lifecycle_state, link)
+        old_state, time_ms = self._alarms_repo.update_alarm(tenant_id, alarm_id,
+                                                            new_state,
+                                                            lifecycle_state, link)
 
         # alarm_definition_id is the same for all rows.
         alarm_definition_id = sub_alarm_rows[0]['alarm_definition_id']
@@ -168,7 +168,8 @@ class Alarms(alarms_api_v2.AlarmsV2API,
                 self._send_alarm_transitioned_event(tenant_id, alarm_id,
                                                     alarm_definition_row,
                                                     alarm_metric_rows,
-                                                    old_state, new_state)
+                                                    old_state, new_state,
+                                                    time_ms)
 
     @resource.resource_try_catch_block
     def _alarm_patch(self, tenant_id, alarm_id, new_state, lifecycle_state,
@@ -177,9 +178,9 @@ class Alarms(alarms_api_v2.AlarmsV2API,
         alarm_metric_rows = self._alarms_repo.get_alarm_metrics(alarm_id)
         sub_alarm_rows = self._alarms_repo.get_sub_alarms(tenant_id, alarm_id)
 
-        old_state = self._alarms_repo.update_alarm(tenant_id, alarm_id,
-                                                   new_state,
-                                                   lifecycle_state, link)
+        old_state, time_ms = self._alarms_repo.update_alarm(tenant_id, alarm_id,
+                                                            new_state,
+                                                            lifecycle_state, link)
 
         # alarm_definition_id is the same for all rows.
         alarm_definition_id = sub_alarm_rows[0]['alarm_definition_id']
@@ -203,7 +204,8 @@ class Alarms(alarms_api_v2.AlarmsV2API,
                 self._send_alarm_transitioned_event(tenant_id, alarm_id,
                                                     alarm_definition_row,
                                                     alarm_metric_rows,
-                                                    old_state, new_state)
+                                                    old_state, new_state,
+                                                    time_ms)
 
     @resource.resource_try_catch_block
     def _alarm_delete(self, tenant_id, id):